content/browser/renderer_host/media/media_stream

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This source file includes following definitions.
RandomLabel
ParseStreamType
DoAddLogMessage
GetLogMessageString
ReturnEmptySalt
video_type_
DeviceRequest
SetAudioType
audio_type
SetVideoType
video_type
CreateUIRequest
CreateTabCatureUIRequest
UIRequest
SetState
state
use_fake_ui_
use_fake_ui_
video_capture_manager
audio_input_device_manager
MakeMediaAccessRequest
GenerateStream
CancelRequest
CancelRequest
CancelAllRequests
StopStreamDevice
StopDevice
CloseDevice
EnumerateDevices
DoEnumerateDevices
OpenDevice
EnsureDeviceMonitorStarted
StopRemovedDevices
StopRemovedDevice
StartMonitoring
StartMonitoringOnUIThread
StopMonitoring
GetRequestedDeviceCaptureId
TranslateDeviceIdToSourceId
TranslateSourceIdToDeviceId
ClearEnumerationCache
EnumerationRequired
StartEnumeration
AddRequest
FindRequest
DeleteRequest
PostRequestToUI
SetupRequest
SetupDeviceCaptureRequest
SetupTabCaptureRequest
SetupScreenCaptureRequest
GetDevicesOpenedByRequest
FindExistingRequestedDeviceInfo
FinalizeGenerateStream
FinalizeRequestFailed
FinalizeOpenDevice
FinalizeEnumerateDevices
FinalizeMediaAccessRequest
InitializeDeviceManagersOnIOThread
Opened
HandleRequestDone
Closed
DevicesEnumerated
SendMessageToNativeLog
OnSuspend
OnResume
AddLogMessageOnIOThread
AddLogMessageOnUIThread
HandleAccessRequestResponse
StopMediaStreamFromBrowser
UseFakeDevice
UseFakeUI
WillDestroyCurrentMessageLoop
NotifyDevicesChanged
RequestDone
GetDeviceManager
OnDevicesChanged
OnMediaStreamUIWindowId
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/browser/renderer_host/media/media_stream_manager.h"

#include <list>
#include <vector>

#include "base/bind.h"
#include "base/command_line.h"
#include "base/compiler_specific.h"
#include "base/logging.h"
#include "base/power_monitor/power_monitor.h"
#include "base/rand_util.h"
#include "base/run_loop.h"
#include "base/strings/stringprintf.h"
#include "base/threading/thread.h"
#include "content/browser/browser_main_loop.h"
#include "content/browser/media/capture/web_contents_capture_util.h"
#include "content/browser/renderer_host/media/audio_input_device_manager.h"
#include "content/browser/renderer_host/media/device_request_message_filter.h"
#include "content/browser/renderer_host/media/media_capture_devices_impl.h"
#include "content/browser/renderer_host/media/media_stream_requester.h"
#include "content/browser/renderer_host/media/media_stream_ui_proxy.h"
#include "content/browser/renderer_host/media/video_capture_manager.h"
#include "content/browser/renderer_host/render_process_host_impl.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/content_browser_client.h"
#include "content/public/browser/media_device_id.h"
#include "content/public/browser/media_observer.h"
#include "content/public/browser/media_request_state.h"
#include "content/public/browser/render_process_host.h"
#include "content/public/common/content_switches.h"
#include "content/public/common/media_stream_request.h"
#include "media/audio/audio_manager_base.h"
#include "media/audio/audio_parameters.h"
#include "media/base/channel_layout.h"
#include "url/gurl.h"

#if defined(OS_WIN)
#include "base/win/scoped_com_initializer.h"
#endif

namespace content {

// Forward declaration of DeviceMonitorMac and its only useable method.
class DeviceMonitorMac {
 public:
  void StartMonitoring();
};

namespace {
// Creates a random label used to identify requests.
std::string RandomLabel() {
  // An earlier PeerConnection spec,
  // http://dev.w3.org/2011/webrtc/editor/webrtc.html, specified the
  // MediaStream::label alphabet as containing 36 characters from
  // range: U+0021, U+0023 to U+0027, U+002A to U+002B, U+002D to U+002E,
  // U+0030 to U+0039, U+0041 to U+005A, U+005E to U+007E.
  // Here we use a safe subset.
  static const char kAlphabet[] = "0123456789"
      "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

  std::string label(36, ' ');
  for (size_t i = 0; i < label.size(); ++i) {
    int random_char = base::RandGenerator(sizeof(kAlphabet) - 1);
    label[i] = kAlphabet[random_char];
  }
  return label;
}

void ParseStreamType(const StreamOptions& options,
                     MediaStreamType* audio_type,
                     MediaStreamType* video_type) {
  *audio_type = MEDIA_NO_SERVICE;
  *video_type = MEDIA_NO_SERVICE;
  if (options.audio_requested) {
     std::string audio_stream_source;
     bool mandatory = false;
     if (options.GetFirstAudioConstraintByName(kMediaStreamSource,
                                               &audio_stream_source,
                                               &mandatory)) {
       DCHECK(mandatory);
       // This is tab or screen capture.
       if (audio_stream_source == kMediaStreamSourceTab) {
         *audio_type = content::MEDIA_TAB_AUDIO_CAPTURE;
       } else if (audio_stream_source == kMediaStreamSourceSystem) {
         *audio_type = content::MEDIA_LOOPBACK_AUDIO_CAPTURE;
       }
     } else {
       // This is normal audio device capture.
       *audio_type = MEDIA_DEVICE_AUDIO_CAPTURE;
     }
  }
  if (options.video_requested) {
     std::string video_stream_source;
     bool mandatory = false;
     if (options.GetFirstVideoConstraintByName(kMediaStreamSource,
                                               &video_stream_source,
                                               &mandatory)) {
       DCHECK(mandatory);
       // This is tab or screen capture.
       if (video_stream_source == kMediaStreamSourceTab) {
         *video_type = content::MEDIA_TAB_VIDEO_CAPTURE;
       } else if (video_stream_source == kMediaStreamSourceScreen) {
         *video_type = content::MEDIA_DESKTOP_VIDEO_CAPTURE;
       } else if (video_stream_source == kMediaStreamSourceDesktop) {
         *video_type = content::MEDIA_DESKTOP_VIDEO_CAPTURE;
       }
     } else {
       // This is normal video device capture.
       *video_type = MEDIA_DEVICE_VIDEO_CAPTURE;
     }
  }
}

// Private helper method for SendMessageToNativeLog() that obtains the global
// MediaStreamManager instance on the UI thread before sending |message| to the
// webrtcLoggingPrivate API.
void DoAddLogMessage(const std::string& message) {
  // Must be on the UI thread to access BrowserMainLoop.
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  // May be null in tests.
  // TODO(vrk): Handle this more elegantly by having native log messages become
  // no-ops until MediaStreamManager is aware that a renderer process has
  // started logging. crbug.com/333894
  if (content::BrowserMainLoop::GetInstance()) {
    BrowserThread::PostTask(
        BrowserThread::IO,
        FROM_HERE,
        base::Bind(&MediaStreamManager::AddLogMessageOnIOThread,
                   base::Unretained(content::BrowserMainLoop::GetInstance()
                                        ->media_stream_manager()),
                   message));
  }
}

// Private helper method to generate a string for the log message that lists the
// human readable names of |devices|.
std::string GetLogMessageString(MediaStreamType stream_type,
                                const StreamDeviceInfoArray& devices) {
  std::string output_string =
      base::StringPrintf("Getting devices for stream type %d:\n", stream_type);
  if (devices.empty()) {
    output_string += "No devices found.";
  } else {
    for (StreamDeviceInfoArray::const_iterator it = devices.begin();
         it != devices.end(); ++it) {
      output_string += "  " + it->device.name + "\n";
    }
  }
  return output_string;
}

// Needed for MediaStreamManager::GenerateStream below.
std::string ReturnEmptySalt() {
  return std::string();
}

}  // namespace


// MediaStreamManager::DeviceRequest represents a request to either enumerate
// available devices or open one or more devices.
// TODO(perkj): MediaStreamManager still needs refactoring. I propose we create
// several subclasses of DeviceRequest and move some of the responsibility of
// the MediaStreamManager to the subclasses to get rid of the way too many if
// statements in MediaStreamManager.
class MediaStreamManager::DeviceRequest {
 public:
  DeviceRequest(MediaStreamRequester* requester,
                int requesting_process_id,
                int requesting_view_id,
                int page_request_id,
                const GURL& security_origin,
                bool user_gesture,
                MediaStreamRequestType request_type,
                const StreamOptions& options,
                const ResourceContext::SaltCallback& salt_callback)
      : requester(requester),
        requesting_process_id(requesting_process_id),
        requesting_view_id(requesting_view_id),
        page_request_id(page_request_id),
        security_origin(security_origin),
        user_gesture(user_gesture),
        request_type(request_type),
        options(options),
        salt_callback(salt_callback),
        state_(NUM_MEDIA_TYPES, MEDIA_REQUEST_STATE_NOT_REQUESTED),
        audio_type_(MEDIA_NO_SERVICE),
        video_type_(MEDIA_NO_SERVICE) {
  }

  ~DeviceRequest() {}

  void SetAudioType(MediaStreamType audio_type) {
    DCHECK(IsAudioMediaType(audio_type) || audio_type == MEDIA_NO_SERVICE);
    audio_type_ = audio_type;
  }

  MediaStreamType audio_type() const { return audio_type_; }

  void SetVideoType(MediaStreamType video_type) {
    DCHECK(IsVideoMediaType(video_type) || video_type == MEDIA_NO_SERVICE);
    video_type_ = video_type;
  }

  MediaStreamType video_type() const { return video_type_; }

  // Creates a MediaStreamRequest object that is used by this request when UI
  // is asked for permission and device selection.
  void CreateUIRequest(const std::string& requested_audio_device_id,
                       const std::string& requested_video_device_id) {
    DCHECK(!ui_request_);
    ui_request_.reset(new MediaStreamRequest(requesting_process_id,
                                             requesting_view_id,
                                             page_request_id,
                                             security_origin,
                                             user_gesture,
                                             request_type,
                                             requested_audio_device_id,
                                             requested_video_device_id,
                                             audio_type_,
                                             video_type_));
  }

  // Creates a tab capture specific MediaStreamRequest object that is used by
  // this request when UI is asked for permission and device selection.
  void CreateTabCatureUIRequest(int target_render_process_id,
                                int target_render_view_id,
                                const std::string& tab_capture_id) {
    DCHECK(!ui_request_);
    ui_request_.reset(new MediaStreamRequest(target_render_process_id,
                                             target_render_view_id,
                                             page_request_id,
                                             security_origin,
                                             user_gesture,
                                             request_type,
                                             "",
                                             "",
                                             audio_type_,
                                             video_type_));
    ui_request_->tab_capture_device_id = tab_capture_id;
  }

  const MediaStreamRequest* UIRequest() const { return ui_request_.get(); }

  // Update the request state and notify observers.
  void SetState(MediaStreamType stream_type, MediaRequestState new_state) {
    if (stream_type == NUM_MEDIA_TYPES) {
      for (int i = MEDIA_NO_SERVICE + 1; i < NUM_MEDIA_TYPES; ++i) {
        const MediaStreamType stream_type = static_cast<MediaStreamType>(i);
        state_[stream_type] = new_state;
      }
    } else {
      state_[stream_type] = new_state;
    }

    MediaObserver* media_observer =
        GetContentClient()->browser()->GetMediaObserver();
    if (!media_observer)
      return;

    // If |ui_request_| doesn't exist, it means that the request has not yet
    // been setup fully and there are no valid observers.
    if (!ui_request_)
      return;

    // If we appended a device_id scheme, we want to remove it when notifying
    // observers which may be in different modules since this scheme is only
    // used internally within the content module.
    std::string device_id =
        WebContentsCaptureUtil::StripWebContentsDeviceScheme(
            ui_request_->tab_capture_device_id);

    media_observer->OnMediaRequestStateChanged(
        ui_request_->render_process_id, ui_request_->render_view_id,
        ui_request_->page_request_id, ui_request_->security_origin,
        MediaStreamDevice(stream_type, device_id, device_id), new_state);
  }

  MediaRequestState state(MediaStreamType stream_type) const {
    return state_[stream_type];
  }

  MediaStreamRequester* const requester;  // Can be NULL.


  // The render process id that requested this stream to be generated and that
  // will receive a handle to the MediaStream. This may be different from
  // MediaStreamRequest::render_process_id which in the tab capture case
  // specifies the target renderer from which audio and video is captured.
  const int requesting_process_id;

  // The render view id that requested this stream to be generated and that
  // will receive a handle to the MediaStream. This may be different from
  // MediaStreamRequest::render_view_id which in the tab capture case
  // specifies the target renderer from which audio and video is captured.
  const int requesting_view_id;

  // An ID the render view provided to identify this request.
  const int page_request_id;

  const GURL security_origin;

  const bool user_gesture;

  const MediaStreamRequestType request_type;

  const StreamOptions options;

  ResourceContext::SaltCallback salt_callback;

  StreamDeviceInfoArray devices;

  // Callback to the requester which audio/video devices have been selected.
  // It can be null if the requester has no interest to know the result.
  // Currently it is only used by |DEVICE_ACCESS| type.
  MediaStreamManager::MediaRequestResponseCallback callback;

  scoped_ptr<MediaStreamUIProxy> ui_proxy;

 private:
  std::vector<MediaRequestState> state_;
  scoped_ptr<MediaStreamRequest> ui_request_;
  MediaStreamType audio_type_;
  MediaStreamType video_type_;
};

MediaStreamManager::EnumerationCache::EnumerationCache()
    : valid(false) {
}

MediaStreamManager::EnumerationCache::~EnumerationCache() {
}

MediaStreamManager::MediaStreamManager()
    : audio_manager_(NULL),
      monitoring_started_(false),
      io_loop_(NULL),
      use_fake_ui_(false) {}

MediaStreamManager::MediaStreamManager(media::AudioManager* audio_manager)
    : audio_manager_(audio_manager),
      monitoring_started_(false),
      io_loop_(NULL),
      use_fake_ui_(false) {
  DCHECK(audio_manager_);
  memset(active_enumeration_ref_count_, 0,
         sizeof(active_enumeration_ref_count_));

  // Some unit tests create the MSM in the IO thread and assumes the
  // initialization is done synchronously.
  if (BrowserThread::CurrentlyOn(BrowserThread::IO)) {
    InitializeDeviceManagersOnIOThread();
  } else {
    BrowserThread::PostTask(
        BrowserThread::IO, FROM_HERE,
        base::Bind(&MediaStreamManager::InitializeDeviceManagersOnIOThread,
                   base::Unretained(this)));
  }

  base::PowerMonitor* power_monitor = base::PowerMonitor::Get();
  // BrowserMainLoop always creates the PowerMonitor instance before creating
  // MediaStreamManager, but power_monitor may be NULL in unit tests.
  if (power_monitor)
    power_monitor->AddObserver(this);
}

MediaStreamManager::~MediaStreamManager() {
  DVLOG(1) << "~MediaStreamManager";
  DCHECK(requests_.empty());
  DCHECK(!device_task_runner_);

  base::PowerMonitor* power_monitor = base::PowerMonitor::Get();
  // The PowerMonitor instance owned by BrowserMainLoops always outlives the
  // MediaStreamManager, but it may be NULL in unit tests.
  if (power_monitor)
    power_monitor->RemoveObserver(this);
}

VideoCaptureManager* MediaStreamManager::video_capture_manager() {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DCHECK(video_capture_manager_.get());
  return video_capture_manager_.get();
}

AudioInputDeviceManager* MediaStreamManager::audio_input_device_manager() {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DCHECK(audio_input_device_manager_.get());
  return audio_input_device_manager_.get();
}

std::string MediaStreamManager::MakeMediaAccessRequest(
    int render_process_id,
    int render_view_id,
    int page_request_id,
    const StreamOptions& options,
    const GURL& security_origin,
    const MediaRequestResponseCallback& callback) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  // TODO(perkj): The argument list with NULL parameters to DeviceRequest
  // suggests that this is the wrong design. Can this be refactored?
  DeviceRequest* request = new DeviceRequest(NULL,
                                             render_process_id,
                                             render_view_id,
                                             page_request_id,
                                             security_origin,
                                             false,  // user gesture
                                             MEDIA_DEVICE_ACCESS,
                                             options,
                                             base::Bind(&ReturnEmptySalt));

  const std::string& label = AddRequest(request);

  request->callback = callback;
  // Post a task and handle the request asynchronously. The reason is that the
  // requester won't have a label for the request until this function returns
  // and thus can not handle a response. Using base::Unretained is safe since
  // MediaStreamManager is deleted on the UI thread, after the IO thread has
  // been stopped.
  BrowserThread::PostTask(
      BrowserThread::IO, FROM_HERE,
      base::Bind(&MediaStreamManager::SetupRequest,
                 base::Unretained(this), label));
  return label;
}

void MediaStreamManager::GenerateStream(MediaStreamRequester* requester,
                                        int render_process_id,
                                        int render_view_id,
                                        const ResourceContext::SaltCallback& sc,
                                        int page_request_id,
                                        const StreamOptions& options,
                                        const GURL& security_origin,
                                        bool user_gesture) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DVLOG(1) << "GenerateStream()";
  if (CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kUseFakeUIForMediaStream)) {
    UseFakeUI(scoped_ptr<FakeMediaStreamUIProxy>());
  }

  DeviceRequest* request = new DeviceRequest(requester,
                                             render_process_id,
                                             render_view_id,
                                             page_request_id,
                                             security_origin,
                                             user_gesture,
                                             MEDIA_GENERATE_STREAM,
                                             options,
                                             sc);

  const std::string& label = AddRequest(request);

  // Post a task and handle the request asynchronously. The reason is that the
  // requester won't have a label for the request until this function returns
  // and thus can not handle a response. Using base::Unretained is safe since
  // MediaStreamManager is deleted on the UI thread, after the IO thread has
  // been stopped.
  BrowserThread::PostTask(
      BrowserThread::IO, FROM_HERE,
      base::Bind(&MediaStreamManager::SetupRequest,
                 base::Unretained(this), label));
}

void MediaStreamManager::CancelRequest(int render_process_id,
                                       int render_view_id,
                                       int page_request_id) {
  for (DeviceRequests::const_iterator request_it = requests_.begin();
       request_it != requests_.end(); ++request_it) {
    const DeviceRequest* request = request_it->second;
    if (request->requesting_process_id == render_process_id &&
        request->requesting_view_id == render_view_id &&
        request->page_request_id == page_request_id) {
      CancelRequest(request_it->first);
      return;
    }
  }
  NOTREACHED();
}

void MediaStreamManager::CancelRequest(const std::string& label) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DVLOG(1) << "CancelRequest({label = " << label <<  "})";
  DeviceRequest* request = FindRequest(label);
  if (!request) {
    // The request does not exist.
    LOG(ERROR) << "The request with label = " << label  << " does not exist.";
    return;
  }

  if (request->request_type == MEDIA_ENUMERATE_DEVICES) {
    // It isn't an ideal use of "CancelRequest" to make it a requirement
    // for enumeration requests to be deleted via "CancelRequest" _after_
    // the request has been successfully fulfilled.
    // See note in FinalizeEnumerateDevices for a recommendation on how
    // we should refactor this.
    DeleteRequest(label);
    return;
  }

  // This is a request for opening one or more devices.
  for (StreamDeviceInfoArray::iterator device_it = request->devices.begin();
       device_it != request->devices.end(); ++device_it) {
    MediaRequestState state = request->state(device_it->device.type);
    // If we have not yet requested the device to be opened - just ignore it.
    if (state != MEDIA_REQUEST_STATE_OPENING &&
        state != MEDIA_REQUEST_STATE_DONE) {
      continue;
    }
    // Stop the opening/opened devices of the requests.
    CloseDevice(device_it->device.type, device_it->session_id);
  }

  // Cancel the request if still pending at UI side.
  request->SetState(NUM_MEDIA_TYPES, MEDIA_REQUEST_STATE_CLOSING);
  DeleteRequest(label);
}

void MediaStreamManager::CancelAllRequests(int render_process_id) {
  DeviceRequests::iterator request_it = requests_.begin();
  while (request_it != requests_.end()) {
    if (request_it->second->requesting_process_id != render_process_id) {
      ++request_it;
      continue;
    }

    std::string label = request_it->first;
    ++request_it;
    CancelRequest(label);
  }
}

void MediaStreamManager::StopStreamDevice(int render_process_id,
                                          int render_view_id,
                                          const std::string& device_id) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DVLOG(1) << "StopStreamDevice({render_view_id = " << render_view_id <<  "} "
           << ", {device_id = " << device_id << "})";
  // Find the first request for this |render_process_id| and |render_view_id|
  // of type MEDIA_GENERATE_STREAM that has requested to use |device_id| and
  // stop it.
  for (DeviceRequests::iterator request_it = requests_.begin();
       request_it  != requests_.end(); ++request_it) {
    DeviceRequest* request = request_it->second;
    if (request->requesting_process_id != render_process_id ||
        request->requesting_view_id != render_view_id ||
        request->request_type != MEDIA_GENERATE_STREAM) {
      continue;
    }

    StreamDeviceInfoArray& devices = request->devices;
    for (StreamDeviceInfoArray::iterator device_it = devices.begin();
         device_it != devices.end(); ++device_it) {
      if (device_it->device.id == device_id) {
        StopDevice(device_it->device.type, device_it->session_id);
        return;
      }
    }
  }
}

void MediaStreamManager::StopDevice(MediaStreamType type, int session_id) {
  DVLOG(1) << "StopDevice"
           << "{type = " << type << "}"
           << "{session_id = " << session_id << "}";
  DeviceRequests::iterator request_it = requests_.begin();
  while (request_it != requests_.end()) {
    DeviceRequest* request = request_it->second;
    StreamDeviceInfoArray* devices = &request->devices;
    if (devices->empty()) {
      // There is no device in use yet by this request.
      ++request_it;
      continue;
    }
    StreamDeviceInfoArray::iterator device_it = devices->begin();
    while (device_it != devices->end()) {
      if (device_it->device.type != type ||
          device_it->session_id != session_id) {
        ++device_it;
        continue;
      }

      if (request->state(type) == MEDIA_REQUEST_STATE_DONE)
        CloseDevice(type, session_id);
      device_it = devices->erase(device_it);
    }

    // If this request doesn't have any active devices after a device
    // has been stopped above, remove the request. Note that the request is
    // only deleted if a device as been removed from |devices|.
    if (devices->empty()) {
      std::string label = request_it->first;
      ++request_it;
      DeleteRequest(label);
    } else {
      ++request_it;
    }
  }
}

void MediaStreamManager::CloseDevice(MediaStreamType type, int session_id) {
  DVLOG(1) << "CloseDevice("
           << "{type = " << type <<  "} "
           << "{session_id = " << session_id << "})";
  GetDeviceManager(type)->Close(session_id);

  for (DeviceRequests::iterator request_it = requests_.begin();
       request_it != requests_.end() ; ++request_it) {
    StreamDeviceInfoArray* devices = &request_it->second->devices;
    for (StreamDeviceInfoArray::iterator device_it = devices->begin();
         device_it != devices->end(); ++device_it) {
      if (device_it->session_id == session_id &&
          device_it->device.type == type) {
        // Notify observers that this device is being closed.
        // Note that only one device per type can be opened.
        request_it->second->SetState(type, MEDIA_REQUEST_STATE_CLOSING);
      }
    }
  }
}

std::string MediaStreamManager::EnumerateDevices(
    MediaStreamRequester* requester,
    int render_process_id,
    int render_view_id,
    const ResourceContext::SaltCallback& sc,
    int page_request_id,
    MediaStreamType type,
    const GURL& security_origin) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DCHECK(requester);
  DCHECK(type == MEDIA_DEVICE_AUDIO_CAPTURE ||
         type == MEDIA_DEVICE_VIDEO_CAPTURE);

  DeviceRequest* request = new DeviceRequest(requester,
                                             render_process_id,
                                             render_view_id,
                                             page_request_id,
                                             security_origin,
                                             false,  // user gesture
                                             MEDIA_ENUMERATE_DEVICES,
                                             StreamOptions(),
                                             sc);
  if (IsAudioMediaType(type))
    request->SetAudioType(type);
  else if (IsVideoMediaType(type))
    request->SetVideoType(type);

  const std::string& label = AddRequest(request);
  // Post a task and handle the request asynchronously. The reason is that the
  // requester won't have a label for the request until this function returns
  // and thus can not handle a response. Using base::Unretained is safe since
  // MediaStreamManager is deleted on the UI thread, after the IO thread has
  // been stopped.
  BrowserThread::PostTask(
      BrowserThread::IO, FROM_HERE,
      base::Bind(&MediaStreamManager::DoEnumerateDevices,
                 base::Unretained(this), label));
  return label;
}

void MediaStreamManager::DoEnumerateDevices(const std::string& label) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DeviceRequest* request = FindRequest(label);
  if (!request)
    return;  // This can happen if the request has been canceled.

  MediaStreamType type;
  EnumerationCache* cache;
  if (request->audio_type() == MEDIA_DEVICE_AUDIO_CAPTURE) {
    DCHECK_EQ(MEDIA_NO_SERVICE, request->video_type());
    type = MEDIA_DEVICE_AUDIO_CAPTURE;
    cache = &audio_enumeration_cache_;
  } else {
    DCHECK_EQ(MEDIA_DEVICE_VIDEO_CAPTURE, request->video_type());
    type = MEDIA_DEVICE_VIDEO_CAPTURE;
    cache = &video_enumeration_cache_;
  }

  if (!EnumerationRequired(cache, type)) {
    // Cached device list of this type exists. Just send it out.
    request->SetState(type, MEDIA_REQUEST_STATE_REQUESTED);
    request->devices = cache->devices;
    FinalizeEnumerateDevices(label, request);
  } else {
    StartEnumeration(request);
  }
  DVLOG(1) << "Enumerate Devices ({label = " << label <<  "})";
}

void MediaStreamManager::OpenDevice(MediaStreamRequester* requester,
                                    int render_process_id,
                                    int render_view_id,
                                    const ResourceContext::SaltCallback& sc,
                                    int page_request_id,
                                    const std::string& device_id,
                                    MediaStreamType type,
                                    const GURL& security_origin) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DCHECK(type == MEDIA_DEVICE_AUDIO_CAPTURE ||
         type == MEDIA_DEVICE_VIDEO_CAPTURE);
  DVLOG(1) << "OpenDevice ({page_request_id = " << page_request_id <<  "})";
  StreamOptions options;
  if (IsAudioMediaType(type)) {
    options.audio_requested = true;
    options.mandatory_audio.push_back(
        StreamOptions::Constraint(kMediaStreamSourceInfoId, device_id));
  } else if (IsVideoMediaType(type)) {
    options.video_requested = true;
    options.mandatory_video.push_back(
        StreamOptions::Constraint(kMediaStreamSourceInfoId, device_id));
  } else {
    NOTREACHED();
  }
  DeviceRequest* request = new DeviceRequest(requester,
                                             render_process_id,
                                             render_view_id,
                                             page_request_id,
                                             security_origin,
                                             false,  // user gesture
                                             MEDIA_OPEN_DEVICE,
                                             options,
                                             sc);

  const std::string& label = AddRequest(request);
  // Post a task and handle the request asynchronously. The reason is that the
  // requester won't have a label for the request until this function returns
  // and thus can not handle a response. Using base::Unretained is safe since
  // MediaStreamManager is deleted on the UI thread, after the IO thread has
  // been stopped.
  BrowserThread::PostTask(
      BrowserThread::IO, FROM_HERE,
      base::Bind(&MediaStreamManager::SetupRequest,
                 base::Unretained(this), label));
}

void MediaStreamManager::EnsureDeviceMonitorStarted() {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  StartMonitoring();
}

void MediaStreamManager::StopRemovedDevices(
    const StreamDeviceInfoArray& old_devices,
    const StreamDeviceInfoArray& new_devices) {
  DVLOG(1) << "StopRemovedDevices("
           << "{#old_devices = " << old_devices.size() <<  "} "
           << "{#new_devices = " << new_devices.size() << "})";
  for (StreamDeviceInfoArray::const_iterator old_dev_it = old_devices.begin();
       old_dev_it != old_devices.end(); ++old_dev_it) {
    bool device_found = false;
    StreamDeviceInfoArray::const_iterator new_dev_it = new_devices.begin();
    for (; new_dev_it != new_devices.end(); ++new_dev_it) {
      if (old_dev_it->device.id == new_dev_it->device.id) {
        device_found = true;
        break;
      }
    }

    if (!device_found) {
      // A device has been removed. We need to check if it is used by a
      // MediaStream and in that case cleanup and notify the render process.
      StopRemovedDevice(old_dev_it->device);
    }
  }
}

void MediaStreamManager::StopRemovedDevice(const MediaStreamDevice& device) {
  std::vector<int> session_ids;
  for (DeviceRequests::const_iterator it = requests_.begin();
       it != requests_.end() ; ++it) {
    const DeviceRequest* request = it->second;
    for (StreamDeviceInfoArray::const_iterator device_it =
             request->devices.begin();
         device_it != request->devices.end(); ++device_it) {
      std::string source_id = content::GetHMACForMediaDeviceID(
          request->salt_callback,
          request->security_origin,
          device.id);
      if (device_it->device.id == source_id &&
          device_it->device.type == device.type) {
        session_ids.push_back(device_it->session_id);
        if (it->second->requester) {
          it->second->requester->DeviceStopped(
              it->second->requesting_view_id,
              it->first,
              *device_it);
        }
      }
    }
  }
  for (std::vector<int>::const_iterator it = session_ids.begin();
       it != session_ids.end(); ++it) {
    StopDevice(device.type, *it);
  }

  std::ostringstream oss;
  oss << "Media input device removed: type = " <<
    (device.type == MEDIA_DEVICE_AUDIO_CAPTURE ? "audio" : "video") <<
    ", id = " << device.id << ", name = " << device.name;
  AddLogMessageOnIOThread(oss.str());
}

void MediaStreamManager::StartMonitoring() {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  if (monitoring_started_)
    return;

  if (!base::SystemMonitor::Get())
    return;

  monitoring_started_ = true;
  base::SystemMonitor::Get()->AddDevicesChangedObserver(this);

  // Enumerate both the audio and video devices to cache the device lists
  // and send them to media observer.
  ++active_enumeration_ref_count_[MEDIA_DEVICE_AUDIO_CAPTURE];
  audio_input_device_manager_->EnumerateDevices(MEDIA_DEVICE_AUDIO_CAPTURE);
  ++active_enumeration_ref_count_[MEDIA_DEVICE_VIDEO_CAPTURE];
  video_capture_manager_->EnumerateDevices(MEDIA_DEVICE_VIDEO_CAPTURE);

#if defined(OS_MACOSX)
  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      base::Bind(&MediaStreamManager::StartMonitoringOnUIThread,
                 base::Unretained(this)));
#endif
}

#if defined(OS_MACOSX)
void MediaStreamManager::StartMonitoringOnUIThread() {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);
  BrowserMainLoop* browser_main_loop = content::BrowserMainLoop::GetInstance();
  if (browser_main_loop)
    browser_main_loop->device_monitor_mac()->StartMonitoring();
}
#endif

void MediaStreamManager::StopMonitoring() {
  DCHECK_EQ(base::MessageLoop::current(), io_loop_);
  if (monitoring_started_) {
    base::SystemMonitor::Get()->RemoveDevicesChangedObserver(this);
    monitoring_started_ = false;
    ClearEnumerationCache(&audio_enumeration_cache_);
    ClearEnumerationCache(&video_enumeration_cache_);
  }
}

bool MediaStreamManager::GetRequestedDeviceCaptureId(
    const DeviceRequest* request,
    MediaStreamType type,
    std::string* device_id) const {
  DCHECK(type == MEDIA_DEVICE_AUDIO_CAPTURE ||
         type == MEDIA_DEVICE_VIDEO_CAPTURE);
  const StreamOptions::Constraints* mandatory =
      (type == MEDIA_DEVICE_AUDIO_CAPTURE) ?
          &request->options.mandatory_audio : &request->options.mandatory_video;
  const StreamOptions::Constraints* optional =
      (type == MEDIA_DEVICE_AUDIO_CAPTURE) ?
          &request->options.optional_audio : &request->options.optional_video;

  std::vector<std::string> source_ids;
  StreamOptions::GetConstraintsByName(*mandatory,
                                      kMediaStreamSourceInfoId, &source_ids);
  if (source_ids.size() > 1) {
    LOG(ERROR) << "Only one mandatory " << kMediaStreamSourceInfoId
        << " is supported.";
    return false;
  }
  // If a specific device has been requested we need to find the real device
  // id.
  if (source_ids.size() == 1 &&
      !TranslateSourceIdToDeviceId(type,
                                   request->salt_callback,
                                   request->security_origin,
                                   source_ids[0], device_id)) {
    LOG(WARNING) << "Invalid mandatory " << kMediaStreamSourceInfoId
                 << " = " << source_ids[0] << ".";
    return false;
  }
  // Check for optional audio sourceIDs.
  if (device_id->empty()) {
    StreamOptions::GetConstraintsByName(*optional,
                                        kMediaStreamSourceInfoId,
                                        &source_ids);
    // Find the first sourceID that translates to device. Note that only one
    // device per type can call to GenerateStream is ever opened.
    for (std::vector<std::string>::const_iterator it = source_ids.begin();
         it != source_ids.end(); ++it) {
      if (TranslateSourceIdToDeviceId(type,
                                      request->salt_callback,
                                      request->security_origin,
                                      *it,
                                      device_id)) {
        break;
      }
    }
  }
  return true;
}

void MediaStreamManager::TranslateDeviceIdToSourceId(
    DeviceRequest* request,
    MediaStreamDevice* device) {
  if (request->audio_type() == MEDIA_DEVICE_AUDIO_CAPTURE ||
      request->video_type() == MEDIA_DEVICE_VIDEO_CAPTURE) {
    device->id = content::GetHMACForMediaDeviceID(
        request->salt_callback,
        request->security_origin,
        device->id);
  }
}

bool MediaStreamManager::TranslateSourceIdToDeviceId(
    MediaStreamType stream_type,
    const ResourceContext::SaltCallback& sc,
    const GURL& security_origin,
    const std::string& source_id,
    std::string* device_id) const {
  DCHECK(stream_type == MEDIA_DEVICE_AUDIO_CAPTURE ||
         stream_type == MEDIA_DEVICE_VIDEO_CAPTURE);
  // The source_id can be empty if the constraint is set but empty.
  if (source_id.empty())
    return false;

  const EnumerationCache* cache =
      stream_type == MEDIA_DEVICE_AUDIO_CAPTURE ?
      &audio_enumeration_cache_ : &video_enumeration_cache_;

  // If device monitoring hasn't started, the |device_guid| is not valid.
  if (!cache->valid)
    return false;

  for (StreamDeviceInfoArray::const_iterator it = cache->devices.begin();
       it != cache->devices.end();
       ++it) {
    if (content::DoesMediaDeviceIDMatchHMAC(sc, security_origin, source_id,
                                            it->device.id)) {
      *device_id = it->device.id;
      return true;
    }
  }
  return false;
}

void MediaStreamManager::ClearEnumerationCache(EnumerationCache* cache) {
  DCHECK_EQ(base::MessageLoop::current(), io_loop_);
  cache->valid = false;
}

bool MediaStreamManager::EnumerationRequired(EnumerationCache* cache,
                                             MediaStreamType stream_type) {
  DCHECK_EQ(base::MessageLoop::current(), io_loop_);
  if (stream_type == MEDIA_NO_SERVICE)
    return false;

  DCHECK(stream_type == MEDIA_DEVICE_AUDIO_CAPTURE ||
         stream_type == MEDIA_DEVICE_VIDEO_CAPTURE);

#if defined(OS_ANDROID)
  // There's no SystemMonitor on Android that notifies us when devices are
  // added or removed, so we need to populate the cache on every request.
  // Fortunately, there is an already up-to-date cache in the browser side
  // audio manager that we can rely on, so the performance impact of
  // invalidating the cache like this, is minimal.
  if (stream_type == MEDIA_DEVICE_AUDIO_CAPTURE) {
    // Make sure the cache is marked as invalid so that FinalizeEnumerateDevices
    // will be called at the end of the enumeration.
    ClearEnumerationCache(cache);
  }
#endif
  // If the cache isn't valid, we need to start a full enumeration.
  return !cache->valid;
}

void MediaStreamManager::StartEnumeration(DeviceRequest* request) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  // Start monitoring the devices when doing the first enumeration.
  StartMonitoring();

  // Start enumeration for devices of all requested device types.
  const MediaStreamType streams[] = { request->audio_type(),
                                      request->video_type() };
  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(streams); ++i) {
    if (streams[i] == MEDIA_NO_SERVICE)
      continue;
    request->SetState(streams[i], MEDIA_REQUEST_STATE_REQUESTED);
    DCHECK_GE(active_enumeration_ref_count_[streams[i]], 0);
    if (active_enumeration_ref_count_[streams[i]] == 0) {
      ++active_enumeration_ref_count_[streams[i]];
      GetDeviceManager(streams[i])->EnumerateDevices(streams[i]);
    }
  }
}

std::string MediaStreamManager::AddRequest(DeviceRequest* request) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  // Create a label for this request and verify it is unique.
  std::string unique_label;
  do {
    unique_label = RandomLabel();
  } while (requests_.find(unique_label) != requests_.end());

  requests_.insert(std::make_pair(unique_label, request));

  return unique_label;
}

MediaStreamManager::DeviceRequest*
MediaStreamManager::FindRequest(const std::string& label) const {
  DeviceRequests::const_iterator request_it = requests_.find(label);
  return request_it == requests_.end() ? NULL : request_it->second;
}

void MediaStreamManager::DeleteRequest(const std::string& label) {
  DVLOG(1) << "DeleteRequest({label= " << label << "})";
  DeviceRequests::iterator it = requests_.find(label);
  scoped_ptr<DeviceRequest> request(it->second);
  requests_.erase(it);
}

void MediaStreamManager::PostRequestToUI(const std::string& label,
                                         DeviceRequest* request) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DCHECK(request->UIRequest());
  DVLOG(1) << "PostRequestToUI({label= " << label << "})";

  const MediaStreamType audio_type = request->audio_type();
  const MediaStreamType video_type = request->video_type();

  // Post the request to UI and set the state.
  if (IsAudioMediaType(audio_type))
    request->SetState(audio_type, MEDIA_REQUEST_STATE_PENDING_APPROVAL);
  if (IsVideoMediaType(video_type))
    request->SetState(video_type, MEDIA_REQUEST_STATE_PENDING_APPROVAL);

  if (use_fake_ui_) {
    if (!fake_ui_)
      fake_ui_.reset(new FakeMediaStreamUIProxy());

    MediaStreamDevices devices;
    if (audio_enumeration_cache_.valid) {
      for (StreamDeviceInfoArray::const_iterator it =
               audio_enumeration_cache_.devices.begin();
           it != audio_enumeration_cache_.devices.end(); ++it) {
        devices.push_back(it->device);
      }
    }
    if (video_enumeration_cache_.valid) {
      for (StreamDeviceInfoArray::const_iterator it =
               video_enumeration_cache_.devices.begin();
           it != video_enumeration_cache_.devices.end(); ++it) {
        devices.push_back(it->device);
      }
    }

    fake_ui_->SetAvailableDevices(devices);

    request->ui_proxy = fake_ui_.Pass();
  } else {
    request->ui_proxy = MediaStreamUIProxy::Create();
  }

  request->ui_proxy->RequestAccess(
      *request->UIRequest(),
      base::Bind(&MediaStreamManager::HandleAccessRequestResponse,
                 base::Unretained(this), label));
}

void MediaStreamManager::SetupRequest(const std::string& label) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DeviceRequest* request = FindRequest(label);
  if (!request) {
    DVLOG(1) << "SetupRequest label " << label << " doesn't exist!!";
    return;  // This can happen if the request has been canceled.
  }

  if (!request->security_origin.is_valid()) {
    LOG(ERROR) << "Invalid security origin. "
               << request->security_origin;
    FinalizeRequestFailed(label,
                          request,
                          MEDIA_DEVICE_INVALID_SECURITY_ORIGIN);
    return;
  }

  MediaStreamType audio_type = MEDIA_NO_SERVICE;
  MediaStreamType video_type = MEDIA_NO_SERVICE;
  ParseStreamType(request->options, &audio_type, &video_type);
  request->SetAudioType(audio_type);
  request->SetVideoType(video_type);

  bool is_web_contents_capture =
      audio_type == MEDIA_TAB_AUDIO_CAPTURE ||
      video_type == MEDIA_TAB_VIDEO_CAPTURE;
  if (is_web_contents_capture && !SetupTabCaptureRequest(request)) {
    FinalizeRequestFailed(label,
                          request,
                          MEDIA_DEVICE_TAB_CAPTURE_FAILURE);
    return;
  }

  bool is_screen_capture =
      video_type == MEDIA_DESKTOP_VIDEO_CAPTURE;
  if (is_screen_capture && !SetupScreenCaptureRequest(request)) {
    FinalizeRequestFailed(label,
                          request,
                          MEDIA_DEVICE_SCREEN_CAPTURE_FAILURE);
    return;
  }

  if (!is_web_contents_capture && !is_screen_capture) {
    if (EnumerationRequired(&audio_enumeration_cache_, audio_type) ||
        EnumerationRequired(&video_enumeration_cache_, video_type)) {
      // Enumerate the devices if there is no valid device lists to be used.
      StartEnumeration(request);
      return;
    } else {
        // Cache is valid, so log the cached devices for MediaStream requests.
      if (request->request_type == MEDIA_GENERATE_STREAM) {
        std::string log_message("Using cached devices for request.\n");
        if (audio_type != MEDIA_NO_SERVICE) {
          log_message +=
              GetLogMessageString(audio_type, audio_enumeration_cache_.devices);
        }
        if (video_type != MEDIA_NO_SERVICE) {
          log_message +=
              GetLogMessageString(video_type, video_enumeration_cache_.devices);
        }
        SendMessageToNativeLog(log_message);
      }
    }

    if (!SetupDeviceCaptureRequest(request)) {
      FinalizeRequestFailed(label, request, MEDIA_DEVICE_NO_HARDWARE);
      return;
    }
  }
  PostRequestToUI(label, request);
}

bool MediaStreamManager::SetupDeviceCaptureRequest(DeviceRequest* request) {
  DCHECK((request->audio_type() == MEDIA_DEVICE_AUDIO_CAPTURE ||
          request->audio_type() == MEDIA_NO_SERVICE) &&
         (request->video_type() == MEDIA_DEVICE_VIDEO_CAPTURE ||
          request->video_type() == MEDIA_NO_SERVICE));
  std::string audio_device_id;
  if (request->options.audio_requested &&
      !GetRequestedDeviceCaptureId(request, request->audio_type(),
                                     &audio_device_id)) {
    return false;
  }

  std::string video_device_id;
  if (request->options.video_requested &&
      !GetRequestedDeviceCaptureId(request, request->video_type(),
                                   &video_device_id)) {
    return false;
  }
  request->CreateUIRequest(audio_device_id, video_device_id);
  DVLOG(3) << "Audio requested " << request->options.audio_requested
           << " device id = " << audio_device_id
           << "Video requested " << request->options.video_requested
           << " device id = " << video_device_id;
  return true;
}

bool MediaStreamManager::SetupTabCaptureRequest(DeviceRequest* request) {
  DCHECK(request->audio_type() == MEDIA_TAB_AUDIO_CAPTURE ||
         request->video_type() == MEDIA_TAB_VIDEO_CAPTURE);

  std::string capture_device_id;
  bool mandatory_audio = false;
  bool mandatory_video = false;
  if (!request->options.GetFirstAudioConstraintByName(kMediaStreamSourceId,
                                                      &capture_device_id,
                                                      &mandatory_audio) &&
      !request->options.GetFirstVideoConstraintByName(kMediaStreamSourceId,
                                                      &capture_device_id,
                                                      &mandatory_video)) {
    return false;
  }
  DCHECK(mandatory_audio || mandatory_video);

  // Customize options for a WebContents based capture.
  int target_render_process_id = 0;
  int target_render_view_id = 0;

  // TODO(justinlin): Can't plumb audio mirroring using stream type right
  // now, so plumbing by device_id. Will revisit once it's refactored.
  // http://crbug.com/163100
  std::string tab_capture_device_id =
      WebContentsCaptureUtil::AppendWebContentsDeviceScheme(capture_device_id);

  bool has_valid_device_id = WebContentsCaptureUtil::ExtractTabCaptureTarget(
      tab_capture_device_id, &target_render_process_id,
      &target_render_view_id);
  if (!has_valid_device_id ||
      (request->audio_type() != MEDIA_TAB_AUDIO_CAPTURE &&
       request->audio_type() != MEDIA_NO_SERVICE) ||
      (request->video_type() != MEDIA_TAB_VIDEO_CAPTURE &&
       request->video_type() != MEDIA_NO_SERVICE)) {
    return false;
  }

  request->CreateTabCatureUIRequest(target_render_process_id,
                                    target_render_view_id,
                                    tab_capture_device_id);

  DVLOG(3) << "SetupTabCaptureRequest "
           << ", {tab_capture_device_id = " << tab_capture_device_id <<  "}"
           << ", {target_render_process_id = " << target_render_process_id
           << "}"
           << ", {target_render_view_id = " << target_render_view_id << "}";
  return true;
}

bool MediaStreamManager::SetupScreenCaptureRequest(DeviceRequest* request) {
  DCHECK(request->audio_type() == MEDIA_LOOPBACK_AUDIO_CAPTURE ||
         request->video_type() == MEDIA_DESKTOP_VIDEO_CAPTURE);

  // For screen capture we only support two valid combinations:
  // (1) screen video capture only, or
  // (2) screen video capture with loopback audio capture.
  if (request->video_type() != MEDIA_DESKTOP_VIDEO_CAPTURE ||
      (request->audio_type() != MEDIA_NO_SERVICE &&
       request->audio_type() != MEDIA_LOOPBACK_AUDIO_CAPTURE)) {
    LOG(ERROR) << "Invalid screen capture request.";
    return false;
  }

  std::string video_device_id;
  if (request->video_type() == MEDIA_DESKTOP_VIDEO_CAPTURE) {
    std::string video_stream_source;
    bool mandatory = false;
    if (!request->options.GetFirstVideoConstraintByName(
        kMediaStreamSource,
        &video_stream_source,
        &mandatory)) {
      LOG(ERROR) << kMediaStreamSource << " not found.";
      return false;
    }
    DCHECK(mandatory);

    if (video_stream_source == kMediaStreamSourceDesktop) {
      if (!request->options.GetFirstVideoConstraintByName(
          kMediaStreamSourceId,
          &video_device_id,
          &mandatory)) {
        LOG(ERROR) << kMediaStreamSourceId << " not found.";
        return false;
      }
      DCHECK(mandatory);
    }
  }

  request->CreateUIRequest("", video_device_id);
  return true;
}

StreamDeviceInfoArray MediaStreamManager::GetDevicesOpenedByRequest(
    const std::string& label) const {
  DeviceRequest* request = FindRequest(label);
  if (!request)
    return StreamDeviceInfoArray();
  return request->devices;
}

bool MediaStreamManager::FindExistingRequestedDeviceInfo(
    const DeviceRequest& new_request,
    const MediaStreamDevice& new_device_info,
    StreamDeviceInfo* existing_device_info,
    MediaRequestState* existing_request_state) const {
  DCHECK(existing_device_info);
  DCHECK(existing_request_state);

  std::string source_id = content::GetHMACForMediaDeviceID(
      new_request.salt_callback,
      new_request.security_origin,
      new_device_info.id);

  for (DeviceRequests::const_iterator it = requests_.begin();
       it != requests_.end() ; ++it) {
    const DeviceRequest* request = it->second;
    if (request->requesting_process_id == new_request.requesting_process_id &&
        request->requesting_view_id == new_request.requesting_view_id &&
        request->request_type == new_request.request_type) {
      for (StreamDeviceInfoArray::const_iterator device_it =
               request->devices.begin();
           device_it != request->devices.end(); ++device_it) {
        if (device_it->device.id == source_id &&
            device_it->device.type == new_device_info.type) {
            *existing_device_info = *device_it;
            *existing_request_state = request->state(device_it->device.type);
          return true;
        }
      }
    }
  }
  return false;
}

void MediaStreamManager::FinalizeGenerateStream(const std::string& label,
                                                DeviceRequest* request) {
  DVLOG(1) << "FinalizeGenerateStream label " << label;
  const StreamDeviceInfoArray& requested_devices = request->devices;

  // Partition the array of devices into audio vs video.
  StreamDeviceInfoArray audio_devices, video_devices;
  for (StreamDeviceInfoArray::const_iterator device_it =
           requested_devices.begin();
       device_it != requested_devices.end(); ++device_it) {
    if (IsAudioMediaType(device_it->device.type)) {
      audio_devices.push_back(*device_it);
    } else if (IsVideoMediaType(device_it->device.type)) {
      video_devices.push_back(*device_it);
    } else {
      NOTREACHED();
    }
  }

  request->requester->StreamGenerated(
      request->requesting_view_id,
      request->page_request_id,
      label, audio_devices, video_devices);
}

void MediaStreamManager::FinalizeRequestFailed(
    const std::string& label,
    DeviceRequest* request,
    content::MediaStreamRequestResult result) {
  if (request->requester)
    request->requester->StreamGenerationFailed(
        request->requesting_view_id,
        request->page_request_id,
        result);

  if (request->request_type == MEDIA_DEVICE_ACCESS &&
      !request->callback.is_null()) {
    request->callback.Run(MediaStreamDevices(), request->ui_proxy.Pass());
  }

  DeleteRequest(label);
}

void MediaStreamManager::FinalizeOpenDevice(const std::string& label,
                                            DeviceRequest* request) {
  const StreamDeviceInfoArray& requested_devices = request->devices;
  request->requester->DeviceOpened(request->requesting_view_id,
                                   request->page_request_id,
                                   label, requested_devices.front());
}

void MediaStreamManager::FinalizeEnumerateDevices(const std::string& label,
                                                  DeviceRequest* request) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DCHECK_EQ(request->request_type, MEDIA_ENUMERATE_DEVICES);

  if (request->security_origin.is_valid()) {
    for (StreamDeviceInfoArray::iterator it = request->devices.begin();
         it != request->devices.end(); ++it) {
      TranslateDeviceIdToSourceId(request, &it->device);
    }
  } else {
    request->devices.clear();
  }

  request->requester->DevicesEnumerated(
      request->requesting_view_id,
      request->page_request_id,
      label,
      request->devices);

  // TODO(tommi):
  // Ideally enumeration requests should be deleted once they have been served
  // (as any request).  However, this implementation mixes requests and
  // notifications together so enumeration requests are kept open by some
  // implementations (only Pepper?) and enumerations are done again when
  // device notifications are fired.
  // Implementations that just want to request the device list and be done
  // (e.g. DeviceRequestMessageFilter), they must (confusingly) call
  // CancelRequest() after the request has been fulfilled.  This is not
  // obvious, not consistent in this class (see e.g. FinalizeMediaAccessRequest)
  // and can lead to subtle bugs (requests not deleted at all deleted too
  // early).
  //
  // Basically, it is not clear that using requests as an additional layer on
  // top of device notifications is necessary or good.
  //
  // To add to this, MediaStreamManager currently relies on the external
  // implementations of MediaStreamRequester to delete enumeration requests via
  // CancelRequest and e.g. DeviceRequestMessageFilter does this.  However the
  // Pepper implementation does not seem to to this at all (and from what I can
  // see, it is the only implementation that uses an enumeration request as a
  // notification mechanism).
  //
  // We should decouple notifications from enumeration requests and once that
  // has been done, remove the requirement to call CancelRequest() to delete
  // enumeration requests and uncomment the following line:
  //
  // DeleteRequest(label);
}

void MediaStreamManager::FinalizeMediaAccessRequest(
    const std::string& label,
    DeviceRequest* request,
    const MediaStreamDevices& devices) {
  if (!request->callback.is_null())
    request->callback.Run(devices, request->ui_proxy.Pass());

  // Delete the request since it is done.
  DeleteRequest(label);
}

void MediaStreamManager::InitializeDeviceManagersOnIOThread() {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  if (device_task_runner_)
    return;

  device_task_runner_ = audio_manager_->GetWorkerTaskRunner();

  audio_input_device_manager_ = new AudioInputDeviceManager(audio_manager_);
  audio_input_device_manager_->Register(this, device_task_runner_);

  video_capture_manager_ = new VideoCaptureManager();
  video_capture_manager_->Register(this, device_task_runner_);

  // We want to be notified of IO message loop destruction to delete the thread
  // and the device managers.
  io_loop_ = base::MessageLoop::current();
  io_loop_->AddDestructionObserver(this);

  if (CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kUseFakeDeviceForMediaStream)) {
    DVLOG(1) << "Using fake device";
    UseFakeDevice();
  }
}

void MediaStreamManager::Opened(MediaStreamType stream_type,
                                int capture_session_id) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DVLOG(1) << "Opened({stream_type = " << stream_type <<  "} "
           << "{capture_session_id = " << capture_session_id << "})";
  // Find the request(s) containing this device and mark it as used.
  // It can be used in several requests since the same device can be
  // requested from the same web page.
  for (DeviceRequests::iterator request_it = requests_.begin();
       request_it != requests_.end(); ++request_it) {
    const std::string& label = request_it->first;
    DeviceRequest* request = request_it->second;
    StreamDeviceInfoArray* devices = &(request->devices);
    for (StreamDeviceInfoArray::iterator device_it = devices->begin();
         device_it != devices->end(); ++device_it) {
      if (device_it->device.type == stream_type &&
          device_it->session_id == capture_session_id) {
        CHECK(request->state(device_it->device.type) ==
            MEDIA_REQUEST_STATE_OPENING);
        // We've found a matching request.
        request->SetState(device_it->device.type, MEDIA_REQUEST_STATE_DONE);

        if (IsAudioMediaType(device_it->device.type)) {
          // Store the native audio parameters in the device struct.
          // TODO(xians): Handle the tab capture sample rate/channel layout
          // in AudioInputDeviceManager::Open().
          if (device_it->device.type != content::MEDIA_TAB_AUDIO_CAPTURE) {
            const StreamDeviceInfo* info =
                audio_input_device_manager_->GetOpenedDeviceInfoById(
                    device_it->session_id);
            device_it->device.input = info->device.input;
            device_it->device.matched_output = info->device.matched_output;
          }
        }
        if (RequestDone(*request))
          HandleRequestDone(label, request);
        break;
      }
    }
  }
}

void MediaStreamManager::HandleRequestDone(const std::string& label,
                                           DeviceRequest* request) {
  DCHECK(RequestDone(*request));
  DVLOG(1) << "HandleRequestDone("
           << ", {label = " << label <<  "})";

  switch (request->request_type) {
    case MEDIA_OPEN_DEVICE:
      FinalizeOpenDevice(label, request);
      break;
    case MEDIA_GENERATE_STREAM: {
      FinalizeGenerateStream(label, request);
      break;
    }
    default:
      NOTREACHED();
      break;
  }

  if (request->ui_proxy.get()) {
    request->ui_proxy->OnStarted(
        base::Bind(&MediaStreamManager::StopMediaStreamFromBrowser,
                   base::Unretained(this),
                   label),
        base::Bind(&MediaStreamManager::OnMediaStreamUIWindowId,
                   base::Unretained(this),
                   request->video_type(),
                   request->devices));
  }
}

void MediaStreamManager::Closed(MediaStreamType stream_type,
                                int capture_session_id) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
}

void MediaStreamManager::DevicesEnumerated(
    MediaStreamType stream_type, const StreamDeviceInfoArray& devices) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DVLOG(1) << "DevicesEnumerated("
           << "{stream_type = " << stream_type << "})" << std::endl;

  std::string log_message = "New device enumeration result:\n" +
                            GetLogMessageString(stream_type, devices);
  SendMessageToNativeLog(log_message);

  // Only cache the device list when the device list has been changed.
  bool need_update_clients = false;
  EnumerationCache* cache =
      stream_type == MEDIA_DEVICE_AUDIO_CAPTURE ?
      &audio_enumeration_cache_ : &video_enumeration_cache_;
  if (!cache->valid ||
      devices.size() != cache->devices.size() ||
      !std::equal(devices.begin(), devices.end(), cache->devices.begin(),
                  StreamDeviceInfo::IsEqual)) {
    StopRemovedDevices(cache->devices, devices);
    cache->devices = devices;
    need_update_clients = true;

    // The device might not be able to be enumerated when it is not warmed up,
    // for example, when the machine just wakes up from sleep. We set the cache
    // to be invalid so that the next media request will trigger the
    // enumeration again. See issue/317673.
    cache->valid = !devices.empty();
 }

  if (need_update_clients && monitoring_started_)
    NotifyDevicesChanged(stream_type, devices);

  // Publish the result for all requests waiting for device list(s).
  // Find the requests waiting for this device list, store their labels and
  // release the iterator before calling device settings. We might get a call
  // back from device_settings that will need to iterate through devices.
  std::list<std::string> label_list;
  for (DeviceRequests::iterator it = requests_.begin(); it != requests_.end();
       ++it) {
    if (it->second->state(stream_type) == MEDIA_REQUEST_STATE_REQUESTED &&
        (it->second->audio_type() == stream_type ||
         it->second->video_type() == stream_type)) {
      if (it->second->request_type != MEDIA_ENUMERATE_DEVICES)
        it->second->SetState(stream_type, MEDIA_REQUEST_STATE_PENDING_APPROVAL);
      label_list.push_back(it->first);
    }
  }

  for (std::list<std::string>::iterator it = label_list.begin();
       it != label_list.end(); ++it) {
    DeviceRequest* request = FindRequest(*it);
    switch (request->request_type) {
      case MEDIA_ENUMERATE_DEVICES:
        if (need_update_clients && request->requester) {
          request->devices = devices;
          FinalizeEnumerateDevices(*it, request);
        }
        break;
      default:
        if (request->state(request->audio_type()) ==
                MEDIA_REQUEST_STATE_REQUESTED ||
            request->state(request->video_type()) ==
                MEDIA_REQUEST_STATE_REQUESTED) {
          // We are doing enumeration for other type of media, wait until it is
          // all done before posting the request to UI because UI needs
          // the device lists to handle the request.
          break;
        }
        if (!SetupDeviceCaptureRequest(request)) {
          FinalizeRequestFailed(*it,
                                request,
                                MEDIA_DEVICE_NO_HARDWARE);
        } else {
          PostRequestToUI(*it, request);
        }
        break;
    }
  }
  label_list.clear();
  --active_enumeration_ref_count_[stream_type];
  DCHECK_GE(active_enumeration_ref_count_[stream_type], 0);
}

// static
void MediaStreamManager::SendMessageToNativeLog(const std::string& message) {
  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      base::Bind(DoAddLogMessage, message));
}

void MediaStreamManager::OnSuspend() {
  SendMessageToNativeLog("Power state suspended.");
}

void MediaStreamManager::OnResume() {
  SendMessageToNativeLog("Power state resumed.");
}

void MediaStreamManager::AddLogMessageOnIOThread(const std::string& message) {
  // Get render process ids on the IO thread.
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  // Grab all unique process ids that request a MediaStream or have a
  // MediaStream running.
  std::set<int> requesting_process_ids;
  for (DeviceRequests::const_iterator it = requests_.begin();
       it != requests_.end(); ++it) {
    DeviceRequest* request = it->second;
    if (request->request_type == MEDIA_GENERATE_STREAM)
      requesting_process_ids.insert(request->requesting_process_id);
  }

  // MediaStreamManager is a singleton in BrowserMainLoop, which owns the UI
  // thread. MediaStreamManager has the same lifetime as the UI thread, so it is
  // safe to use base::Unretained.
  BrowserThread::PostTask(
      BrowserThread::UI,
      FROM_HERE,
      base::Bind(&MediaStreamManager::AddLogMessageOnUIThread,
                 base::Unretained(this),
                 requesting_process_ids,
                 message));
}

void MediaStreamManager::AddLogMessageOnUIThread(
    const std::set<int>& requesting_process_ids,
    const std::string& message) {
#if defined(ENABLE_WEBRTC)
  // Must be on the UI thread to access RenderProcessHost from process ID.
  DCHECK_CURRENTLY_ON(BrowserThread::UI);

  for (std::set<int>::const_iterator it = requesting_process_ids.begin();
       it != requesting_process_ids.end(); ++it) {
    // Log the message to all renderers that are requesting a MediaStream or
    // have a MediaStream running.
    content::RenderProcessHostImpl* render_process_host_impl =
        static_cast<content::RenderProcessHostImpl*>(
            content::RenderProcessHost::FromID(*it));
    if (render_process_host_impl)
      render_process_host_impl->WebRtcLogMessage(message);
  }
#endif
}

void MediaStreamManager::HandleAccessRequestResponse(
    const std::string& label,
    const MediaStreamDevices& devices,
    content::MediaStreamRequestResult result) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DVLOG(1) << "HandleAccessRequestResponse("
           << ", {label = " << label <<  "})";

  DeviceRequest* request = FindRequest(label);
  if (!request) {
    // The request has been canceled before the UI returned.
    return;
  }

  if (request->request_type == MEDIA_DEVICE_ACCESS) {
    FinalizeMediaAccessRequest(label, request, devices);
    return;
  }

  // Handle the case when the request was denied.
  if (result != MEDIA_DEVICE_OK) {
    FinalizeRequestFailed(label, request, result);
    return;
  }
  DCHECK(!devices.empty());

  // Process all newly-accepted devices for this request.
  bool found_audio = false;
  bool found_video = false;
  for (MediaStreamDevices::const_iterator device_it = devices.begin();
       device_it != devices.end(); ++device_it) {
    StreamDeviceInfo device_info;
    device_info.device = *device_it;

    // TODO(justinlin): Nicer way to do this?
    // Re-append the device's id since we lost it when posting request to UI.
    if (device_info.device.type == content::MEDIA_TAB_VIDEO_CAPTURE ||
        device_info.device.type == content::MEDIA_TAB_AUDIO_CAPTURE) {
      device_info.device.id = request->UIRequest()->tab_capture_device_id;

      // Initialize the sample_rate and channel_layout here since for audio
      // mirroring, we don't go through EnumerateDevices where these are usually
      // initialized.
      if (device_info.device.type == content::MEDIA_TAB_AUDIO_CAPTURE) {
        const media::AudioParameters parameters =
            audio_manager_->GetDefaultOutputStreamParameters();
        int sample_rate = parameters.sample_rate();
        // If we weren't able to get the native sampling rate or the sample_rate
        // is outside the valid range for input devices set reasonable defaults.
        if (sample_rate <= 0 || sample_rate > 96000)
          sample_rate = 44100;

        device_info.device.input.sample_rate = sample_rate;
        device_info.device.input.channel_layout = media::CHANNEL_LAYOUT_STEREO;
      }
    }

    if (device_info.device.type == request->audio_type()) {
      found_audio = true;
    } else if (device_info.device.type == request->video_type()) {
      found_video = true;
    }

    // If this is request for a new MediaStream, a device is only opened once
    // per render view. This is so that the permission to use a device can be
    // revoked by a single call to StopStreamDevice regardless of how many
    // MediaStreams it is being used in.
    if (request->request_type == MEDIA_GENERATE_STREAM) {
      MediaRequestState state;
      if (FindExistingRequestedDeviceInfo(*request,
                                          device_info.device,
                                          &device_info,
                                          &state)) {
        request->devices.push_back(device_info);
        request->SetState(device_info.device.type, state);
        DVLOG(1) << "HandleAccessRequestResponse - device already opened "
                 << ", {label = " << label <<  "}"
                 << ", device_id = " << device_it->id << "}";
        continue;
      }
    }
    device_info.session_id =
        GetDeviceManager(device_info.device.type)->Open(device_info);
    TranslateDeviceIdToSourceId(request, &device_info.device);
    request->devices.push_back(device_info);

    request->SetState(device_info.device.type, MEDIA_REQUEST_STATE_OPENING);
    DVLOG(1) << "HandleAccessRequestResponse - opening device "
             << ", {label = " << label <<  "}"
             << ", {device_id = " << device_info.device.id << "}"
             << ", {session_id = " << device_info.session_id << "}";
  }

  // Check whether we've received all stream types requested.
  if (!found_audio && IsAudioMediaType(request->audio_type())) {
    request->SetState(request->audio_type(), MEDIA_REQUEST_STATE_ERROR);
    DVLOG(1) << "Set no audio found label " << label;
  }

  if (!found_video && IsVideoMediaType(request->video_type()))
    request->SetState(request->video_type(), MEDIA_REQUEST_STATE_ERROR);

  if (RequestDone(*request))
    HandleRequestDone(label, request);
}

void MediaStreamManager::StopMediaStreamFromBrowser(const std::string& label) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  DeviceRequest* request = FindRequest(label);
  if (!request)
    return;

  // Notify renderers that the devices in the stream will be stopped.
  if (request->requester) {
    for (StreamDeviceInfoArray::iterator device_it = request->devices.begin();
         device_it != request->devices.end(); ++device_it) {
      request->requester->DeviceStopped(request->requesting_view_id,
                                        label,
                                        *device_it);
    }
  }

  CancelRequest(label);
}

void MediaStreamManager::UseFakeDevice() {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  video_capture_manager()->UseFakeDevice();
  audio_input_device_manager()->UseFakeDevice();
}

void MediaStreamManager::UseFakeUI(scoped_ptr<FakeMediaStreamUIProxy> fake_ui) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  use_fake_ui_ = true;
  fake_ui_ = fake_ui.Pass();
}

void MediaStreamManager::WillDestroyCurrentMessageLoop() {
  DVLOG(3) << "MediaStreamManager::WillDestroyCurrentMessageLoop()";
  DCHECK_EQ(base::MessageLoop::current(), io_loop_);
  DCHECK(requests_.empty());
  if (device_task_runner_) {
    StopMonitoring();

    video_capture_manager_->Unregister();
    audio_input_device_manager_->Unregister();
    device_task_runner_ = NULL;
  }

  audio_input_device_manager_ = NULL;
  video_capture_manager_ = NULL;
}

void MediaStreamManager::NotifyDevicesChanged(
    MediaStreamType stream_type,
    const StreamDeviceInfoArray& devices) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  MediaObserver* media_observer =
      GetContentClient()->browser()->GetMediaObserver();
  if (media_observer == NULL)
    return;

  // Map the devices to MediaStreamDevices.
  MediaStreamDevices new_devices;
  for (StreamDeviceInfoArray::const_iterator it = devices.begin();
       it != devices.end(); ++it) {
    new_devices.push_back(it->device);
  }

  if (IsAudioMediaType(stream_type)) {
    MediaCaptureDevicesImpl::GetInstance()->OnAudioCaptureDevicesChanged(
        new_devices);
    media_observer->OnAudioCaptureDevicesChanged();
  } else if (IsVideoMediaType(stream_type)) {
    MediaCaptureDevicesImpl::GetInstance()->OnVideoCaptureDevicesChanged(
        new_devices);
    media_observer->OnVideoCaptureDevicesChanged();
  } else {
    NOTREACHED();
  }
}

bool MediaStreamManager::RequestDone(const DeviceRequest& request) const {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  const bool requested_audio = IsAudioMediaType(request.audio_type());
  const bool requested_video = IsVideoMediaType(request.video_type());

  const bool audio_done =
      !requested_audio ||
      request.state(request.audio_type()) == MEDIA_REQUEST_STATE_DONE ||
      request.state(request.audio_type()) == MEDIA_REQUEST_STATE_ERROR;
  if (!audio_done)
    return false;

  const bool video_done =
      !requested_video ||
      request.state(request.video_type()) == MEDIA_REQUEST_STATE_DONE ||
      request.state(request.video_type()) == MEDIA_REQUEST_STATE_ERROR;
  if (!video_done)
    return false;

  return true;
}

MediaStreamProvider* MediaStreamManager::GetDeviceManager(
    MediaStreamType stream_type) {
  if (IsVideoMediaType(stream_type)) {
    return video_capture_manager();
  } else if (IsAudioMediaType(stream_type)) {
    return audio_input_device_manager();
  }
  NOTREACHED();
  return NULL;
}

void MediaStreamManager::OnDevicesChanged(
    base::SystemMonitor::DeviceType device_type) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  // NOTE: This method is only called in response to physical audio/video device
  // changes (from the operating system).

  MediaStreamType stream_type;
  if (device_type == base::SystemMonitor::DEVTYPE_AUDIO_CAPTURE) {
    stream_type = MEDIA_DEVICE_AUDIO_CAPTURE;
  } else if (device_type == base::SystemMonitor::DEVTYPE_VIDEO_CAPTURE) {
    stream_type = MEDIA_DEVICE_VIDEO_CAPTURE;
  } else {
    return;  // Uninteresting device change.
  }

  // Always do enumeration even though some enumeration is in progress,
  // because those enumeration commands could be sent before these devices
  // change.
  ++active_enumeration_ref_count_[stream_type];
  GetDeviceManager(stream_type)->EnumerateDevices(stream_type);
}

void MediaStreamManager::OnMediaStreamUIWindowId(MediaStreamType video_type,
                                                 StreamDeviceInfoArray devices,
                                                 gfx::NativeViewId window_id) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  if (!window_id)
    return;

  // Pass along for desktop capturing. Ignored for other stream types.
  if (video_type == MEDIA_DESKTOP_VIDEO_CAPTURE) {
    for (StreamDeviceInfoArray::iterator it = devices.begin();
         it != devices.end();
         ++it) {
      if (it->device.type == MEDIA_DESKTOP_VIDEO_CAPTURE) {
        video_capture_manager_->SetDesktopCaptureWindowId(it->session_id,
                                                          window_id);
        break;
      }
    }
  }
}

}  // namespace content
/* [<][>][^][v][top][bottom][index][help] */
root/content/browser/renderer_host/media/media_stream_manager.cc

DEFINITIONS
