root/content/browser/renderer_host/media/video_capture_manager.cc

DEFINITIONS

1. IsCaptureFormatSmaller
2. IsCaptureFormatSizeEqual
3. ConsolidateCaptureFormats
4. video_capture_controller
5. supported_formats
6. artificial_device_source_for_testing_
7. Register
8. Unregister
9. EnumerateDevices
10. Open
11. Close
12. UseFakeDevice
13. DoStartDeviceOnDeviceThread
14. StartCaptureForClient
15. StopCaptureForClient
16. GetDeviceSupportedFormats
17. GetDeviceFormatsInUse
18. SetDesktopCaptureWindowId
19. DoStopDeviceOnDeviceThread
20. OnOpened
21. OnClosed
22. OnDevicesInfoEnumerated
23. IsOnDeviceThread
24. GetAvailableDevicesInfoOnDeviceThread
25. GetDeviceEntryForMediaStreamDevice
26. GetDeviceEntryForController
27. DestroyDeviceEntryIfNoClients
28. GetOrCreateDeviceEntry
29. FindDeviceInfoById
30. SetDesktopCaptureWindowIdOnDeviceThread
31. SaveDesktopCaptureWindowIdOnDeviceThread

// 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/video_capture_manager.h"

#include <set>

#include "base/bind.h"
#include "base/command_line.h"
#include "base/logging.h"
#include "base/message_loop/message_loop.h"
#include "base/stl_util.h"
#include "base/task_runner_util.h"
#include "base/threading/sequenced_worker_pool.h"
#include "content/browser/media/capture/web_contents_video_capture_device.h"
#include "content/browser/renderer_host/media/video_capture_controller.h"
#include "content/browser/renderer_host/media/video_capture_controller_event_handler.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/desktop_media_id.h"
#include "content/public/common/content_switches.h"
#include "content/public/common/media_stream_request.h"
#include "media/base/media_switches.h"
#include "media/base/scoped_histogram_timer.h"
#include "media/video/capture/fake_video_capture_device.h"
#include "media/video/capture/file_video_capture_device.h"
#include "media/video/capture/video_capture_device.h"

#if defined(ENABLE_SCREEN_CAPTURE)
#include "content/browser/media/capture/desktop_capture_device.h"
#if defined(USE_AURA)
#include "content/browser/media/capture/desktop_capture_device_aura.h"
#endif
#endif

namespace {

// Compares two VideoCaptureFormat by checking smallest frame_size area, then
// by _largest_ frame_rate. Used to order a VideoCaptureFormats vector so that
// the first entry for a given resolution has the largest frame rate, as needed
// by the ConsolidateCaptureFormats() method.
bool IsCaptureFormatSmaller(const media::VideoCaptureFormat& format1,
                            const media::VideoCaptureFormat& format2) {
  if (format1.frame_size.GetArea() == format2.frame_size.GetArea())
    return format1.frame_rate > format2.frame_rate;
  return format1.frame_size.GetArea() < format2.frame_size.GetArea();
}

bool IsCaptureFormatSizeEqual(const media::VideoCaptureFormat& format1,
                              const media::VideoCaptureFormat& format2) {
  return format1.frame_size.GetArea() == format2.frame_size.GetArea();
}

// This function receives a list of capture formats, removes duplicated
// resolutions while keeping the highest frame rate for each, and forcing I420
// pixel format.
void ConsolidateCaptureFormats(media::VideoCaptureFormats* formats) {
  if (formats->empty())
    return;
  std::sort(formats->begin(), formats->end(), IsCaptureFormatSmaller);
  // Due to the ordering imposed, the largest frame_rate is kept while removing
  // duplicated resolutions.
  media::VideoCaptureFormats::iterator last =
      std::unique(formats->begin(), formats->end(), IsCaptureFormatSizeEqual);
  formats->erase(last, formats->end());
  // Mark all formats as I420, since this is what the renderer side will get
  // anyhow: the actual pixel format is decided at the device level.
  for (media::VideoCaptureFormats::iterator it = formats->begin();
       it != formats->end(); ++it) {
    it->pixel_format = media::PIXEL_FORMAT_I420;
  }
}

}  // namespace

namespace content {

VideoCaptureManager::DeviceEntry::DeviceEntry(
    MediaStreamType stream_type,
    const std::string& id,
    scoped_ptr<VideoCaptureController> controller)
    : stream_type(stream_type),
      id(id),
      video_capture_controller(controller.Pass()) {}

VideoCaptureManager::DeviceEntry::~DeviceEntry() {}

VideoCaptureManager::DeviceInfo::DeviceInfo() {}

VideoCaptureManager::DeviceInfo::DeviceInfo(
    const media::VideoCaptureDevice::Name& name,
    const media::VideoCaptureFormats& supported_formats)
    : name(name),
      supported_formats(supported_formats) {}

VideoCaptureManager::DeviceInfo::~DeviceInfo() {}

VideoCaptureManager::VideoCaptureManager()
    : listener_(NULL),
      new_capture_session_id_(1),
      artificial_device_source_for_testing_(DISABLED) {
}

VideoCaptureManager::~VideoCaptureManager() {
  DCHECK(devices_.empty());
}

void VideoCaptureManager::Register(
    MediaStreamProviderListener* listener,
    const scoped_refptr<base::SingleThreadTaskRunner>& device_task_runner) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DCHECK(!listener_);
  DCHECK(!device_task_runner_.get());
  listener_ = listener;
  device_task_runner_ = device_task_runner;
}

void VideoCaptureManager::Unregister() {
  DCHECK(listener_);
  listener_ = NULL;
}

void VideoCaptureManager::EnumerateDevices(MediaStreamType stream_type) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DVLOG(1) << "VideoCaptureManager::EnumerateDevices, type " << stream_type;
  DCHECK(listener_);
  base::PostTaskAndReplyWithResult(
      device_task_runner_, FROM_HERE,
      base::Bind(&VideoCaptureManager::GetAvailableDevicesInfoOnDeviceThread,
                 this, stream_type, devices_info_cache_),
      base::Bind(&VideoCaptureManager::OnDevicesInfoEnumerated, this,
                 stream_type));
}

int VideoCaptureManager::Open(const StreamDeviceInfo& device_info) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DCHECK(listener_);

  // Generate a new id for the session being opened.
  const media::VideoCaptureSessionId capture_session_id =
      new_capture_session_id_++;

  DCHECK(sessions_.find(capture_session_id) == sessions_.end());
  DVLOG(1) << "VideoCaptureManager::Open, id " << capture_session_id;

  // We just save the stream info for processing later.
  sessions_[capture_session_id] = device_info.device;

  // Notify our listener asynchronously; this ensures that we return
  // |capture_session_id| to the caller of this function before using that same
  // id in a listener event.
  base::MessageLoop::current()->PostTask(FROM_HERE,
      base::Bind(&VideoCaptureManager::OnOpened, this,
                 device_info.device.type, capture_session_id));
  return capture_session_id;
}

void VideoCaptureManager::Close(int capture_session_id) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DCHECK(listener_);
  DVLOG(1) << "VideoCaptureManager::Close, id " << capture_session_id;

  std::map<media::VideoCaptureSessionId, MediaStreamDevice>::iterator
      session_it = sessions_.find(capture_session_id);
  if (session_it == sessions_.end()) {
    NOTREACHED();
    return;
  }

  DeviceEntry* const existing_device = GetDeviceEntryForMediaStreamDevice(
      session_it->second);
  if (existing_device) {
    // Remove any client that is still using the session. This is safe to call
    // even if there are no clients using the session.
    existing_device->video_capture_controller->StopSession(capture_session_id);

    // StopSession() may have removed the last client, so we might need to
    // close the device.
    DestroyDeviceEntryIfNoClients(existing_device);
  }

  // Notify listeners asynchronously, and forget the session.
  base::MessageLoop::current()->PostTask(FROM_HERE,
      base::Bind(&VideoCaptureManager::OnClosed, this, session_it->second.type,
                 capture_session_id));
  sessions_.erase(session_it);
}

void VideoCaptureManager::UseFakeDevice() {
  if (CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kUseFileForFakeVideoCapture)) {
    artificial_device_source_for_testing_ = Y4M_FILE;
  } else {
    artificial_device_source_for_testing_ = TEST_PATTERN;
  }
}

void VideoCaptureManager::DoStartDeviceOnDeviceThread(
    media::VideoCaptureSessionId session_id,
    DeviceEntry* entry,
    const media::VideoCaptureParams& params,
    scoped_ptr<media::VideoCaptureDevice::Client> device_client) {
  SCOPED_UMA_HISTOGRAM_TIMER("Media.VideoCaptureManager.StartDeviceTime");
  DCHECK(IsOnDeviceThread());

  scoped_ptr<media::VideoCaptureDevice> video_capture_device;
  switch (entry->stream_type) {
    case MEDIA_DEVICE_VIDEO_CAPTURE: {
      // We look up the device id from the renderer in our local enumeration
      // since the renderer does not have all the information that might be
      // held in the browser-side VideoCaptureDevice::Name structure.
      DeviceInfo* found = FindDeviceInfoById(entry->id, devices_info_cache_);
      if (found) {
        switch (artificial_device_source_for_testing_) {
          case DISABLED:
            video_capture_device.reset(
                media::VideoCaptureDevice::Create(found->name));
            break;
          case TEST_PATTERN:
            video_capture_device.reset(
                media::FakeVideoCaptureDevice::Create(found->name));
            break;
          case Y4M_FILE:
            video_capture_device.reset(
                media::FileVideoCaptureDevice::Create(found->name));
            break;
        }
      }
      break;
    }
    case MEDIA_TAB_VIDEO_CAPTURE: {
      video_capture_device.reset(
          WebContentsVideoCaptureDevice::Create(entry->id));
      break;
    }
    case MEDIA_DESKTOP_VIDEO_CAPTURE: {
#if defined(ENABLE_SCREEN_CAPTURE)
      DesktopMediaID id = DesktopMediaID::Parse(entry->id);
#if defined(USE_AURA)
      if (id.type == DesktopMediaID::TYPE_AURA_WINDOW) {
        video_capture_device.reset(DesktopCaptureDeviceAura::Create(id));
      } else
#endif
      if (id.type != DesktopMediaID::TYPE_NONE &&
          id.type != DesktopMediaID::TYPE_AURA_WINDOW) {
        video_capture_device = DesktopCaptureDevice::Create(id);
        if (notification_window_ids_.find(session_id) !=
            notification_window_ids_.end()) {
          static_cast<DesktopCaptureDevice*>(video_capture_device.get())
              ->SetNotificationWindowId(notification_window_ids_[session_id]);
        }
      }
#endif  // defined(ENABLE_SCREEN_CAPTURE)
      break;
    }
    default: {
      NOTIMPLEMENTED();
      break;
    }
  }

  if (!video_capture_device) {
    device_client->OnError("Could not create capture device");
    return;
  }

  video_capture_device->AllocateAndStart(params, device_client.Pass());
  entry->video_capture_device = video_capture_device.Pass();
}

void VideoCaptureManager::StartCaptureForClient(
    media::VideoCaptureSessionId session_id,
    const media::VideoCaptureParams& params,
    base::ProcessHandle client_render_process,
    VideoCaptureControllerID client_id,
    VideoCaptureControllerEventHandler* client_handler,
    const DoneCB& done_cb) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DVLOG(1) << "VideoCaptureManager::StartCaptureForClient, "
           << params.requested_format.frame_size.ToString() << ", "
           << params.requested_format.frame_rate << ", #" << session_id << ")";

  DeviceEntry* entry = GetOrCreateDeviceEntry(session_id);
  if (!entry) {
    done_cb.Run(base::WeakPtr<VideoCaptureController>());
    return;
  }

  DCHECK(entry->video_capture_controller);

  // First client starts the device.
  if (entry->video_capture_controller->GetClientCount() == 0) {
    DVLOG(1) << "VideoCaptureManager starting device (type = "
             << entry->stream_type << ", id = " << entry->id << ")";

    device_task_runner_->PostTask(
        FROM_HERE,
        base::Bind(
            &VideoCaptureManager::DoStartDeviceOnDeviceThread,
            this,
            session_id,
            entry,
            params,
            base::Passed(entry->video_capture_controller->NewDeviceClient())));
  }
  // Run the callback first, as AddClient() may trigger OnFrameInfo().
  done_cb.Run(entry->video_capture_controller->GetWeakPtr());
  entry->video_capture_controller->AddClient(
      client_id, client_handler, client_render_process, session_id, params);
}

void VideoCaptureManager::StopCaptureForClient(
    VideoCaptureController* controller,
    VideoCaptureControllerID client_id,
    VideoCaptureControllerEventHandler* client_handler) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DCHECK(controller);
  DCHECK(client_handler);

  DeviceEntry* entry = GetDeviceEntryForController(controller);
  if (!entry) {
    NOTREACHED();
    return;
  }

  // Detach client from controller.
  media::VideoCaptureSessionId session_id =
      controller->RemoveClient(client_id, client_handler);
  DVLOG(1) << "VideoCaptureManager::StopCaptureForClient, session_id = "
           << session_id;

  // If controller has no more clients, delete controller and device.
  DestroyDeviceEntryIfNoClients(entry);
}

bool VideoCaptureManager::GetDeviceSupportedFormats(
    media::VideoCaptureSessionId capture_session_id,
    media::VideoCaptureFormats* supported_formats) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DCHECK(supported_formats->empty());

  std::map<media::VideoCaptureSessionId, MediaStreamDevice>::iterator it =
      sessions_.find(capture_session_id);
  if (it == sessions_.end())
    return false;
  DVLOG(1) << "GetDeviceSupportedFormats for device: " << it->second.name;

  // Return all available formats of the device, regardless its started state.
  DeviceInfo* existing_device =
      FindDeviceInfoById(it->second.id, devices_info_cache_);
  if (existing_device)
    *supported_formats = existing_device->supported_formats;
  return true;
}

bool VideoCaptureManager::GetDeviceFormatsInUse(
    media::VideoCaptureSessionId capture_session_id,
    media::VideoCaptureFormats* formats_in_use) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  DCHECK(formats_in_use->empty());

  std::map<media::VideoCaptureSessionId, MediaStreamDevice>::iterator it =
      sessions_.find(capture_session_id);
  if (it == sessions_.end())
    return false;
  DVLOG(1) << "GetDeviceFormatsInUse for device: " << it->second.name;

  // Return the currently in-use format(s) of the device, if it's started.
  DeviceEntry* device_in_use =
      GetDeviceEntryForMediaStreamDevice(it->second);
  if (device_in_use) {
    // Currently only one format-in-use is supported at the VCC level.
    formats_in_use->push_back(
        device_in_use->video_capture_controller->GetVideoCaptureFormat());
  }
  return true;
}

void VideoCaptureManager::SetDesktopCaptureWindowId(
    media::VideoCaptureSessionId session_id,
    gfx::NativeViewId window_id) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  std::map<media::VideoCaptureSessionId, MediaStreamDevice>::iterator
      session_it = sessions_.find(session_id);
  if (session_it == sessions_.end()) {
    device_task_runner_->PostTask(
        FROM_HERE,
        base::Bind(
            &VideoCaptureManager::SaveDesktopCaptureWindowIdOnDeviceThread,
            this,
            session_id,
            window_id));
    return;
  }

  DeviceEntry* const existing_device =
      GetDeviceEntryForMediaStreamDevice(session_it->second);
  if (!existing_device)
    return;

  DCHECK_EQ(MEDIA_DESKTOP_VIDEO_CAPTURE, existing_device->stream_type);
  DesktopMediaID id = DesktopMediaID::Parse(existing_device->id);
  if (id.type == DesktopMediaID::TYPE_NONE ||
      id.type == DesktopMediaID::TYPE_AURA_WINDOW) {
    return;
  }

  device_task_runner_->PostTask(
      FROM_HERE,
      base::Bind(&VideoCaptureManager::SetDesktopCaptureWindowIdOnDeviceThread,
                 this,
                 existing_device,
                 window_id));
}

void VideoCaptureManager::DoStopDeviceOnDeviceThread(DeviceEntry* entry) {
  SCOPED_UMA_HISTOGRAM_TIMER("Media.VideoCaptureManager.StopDeviceTime");
  DCHECK(IsOnDeviceThread());
  if (entry->video_capture_device) {
    entry->video_capture_device->StopAndDeAllocate();
  }
  entry->video_capture_device.reset();
}

void VideoCaptureManager::OnOpened(
    MediaStreamType stream_type,
    media::VideoCaptureSessionId capture_session_id) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  if (!listener_) {
    // Listener has been removed.
    return;
  }
  listener_->Opened(stream_type, capture_session_id);
}

void VideoCaptureManager::OnClosed(
    MediaStreamType stream_type,
    media::VideoCaptureSessionId capture_session_id) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  if (!listener_) {
    // Listener has been removed.
    return;
  }
  listener_->Closed(stream_type, capture_session_id);
}

void VideoCaptureManager::OnDevicesInfoEnumerated(
    MediaStreamType stream_type,
    const DeviceInfos& new_devices_info_cache) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  if (!listener_) {
    // Listener has been removed.
    return;
  }
  devices_info_cache_ = new_devices_info_cache;

  // Walk the |devices_info_cache_| and transform from VCD::Name to
  // StreamDeviceInfo for return purposes.
  StreamDeviceInfoArray devices;
  for (DeviceInfos::const_iterator it = devices_info_cache_.begin();
       it != devices_info_cache_.end(); ++it) {
    devices.push_back(StreamDeviceInfo(
        stream_type, it->name.GetNameAndModel(), it->name.id()));
  }
  listener_->DevicesEnumerated(stream_type, devices);
}

bool VideoCaptureManager::IsOnDeviceThread() const {
  return device_task_runner_->BelongsToCurrentThread();
}

VideoCaptureManager::DeviceInfos
VideoCaptureManager::GetAvailableDevicesInfoOnDeviceThread(
    MediaStreamType stream_type,
    const DeviceInfos& old_device_info_cache) {
  SCOPED_UMA_HISTOGRAM_TIMER(
      "Media.VideoCaptureManager.GetAvailableDevicesInfoOnDeviceThreadTime");
  DCHECK(IsOnDeviceThread());
  media::VideoCaptureDevice::Names names_snapshot;
  switch (stream_type) {
    case MEDIA_DEVICE_VIDEO_CAPTURE:
      // Cache the latest enumeration of video capture devices.
      // We'll refer to this list again in OnOpen to avoid having to
      // enumerate the devices again.
      switch (artificial_device_source_for_testing_) {
        case DISABLED:
          media::VideoCaptureDevice::GetDeviceNames(&names_snapshot);
          break;
        case TEST_PATTERN:
          media::FakeVideoCaptureDevice::GetDeviceNames(&names_snapshot);
          break;
        case Y4M_FILE:
          media::FileVideoCaptureDevice::GetDeviceNames(&names_snapshot);
          break;
      }
      break;

    case MEDIA_DESKTOP_VIDEO_CAPTURE:
      // Do nothing.
      break;

    default:
      NOTREACHED();
      break;
  }

  // Construct |new_devices_info_cache| with the cached devices that are still
  // present in the system, and remove their names from |names_snapshot|, so we
  // keep there the truly new devices.
  DeviceInfos new_devices_info_cache;
  for (DeviceInfos::const_iterator it_device_info =
           old_device_info_cache.begin();
       it_device_info != old_device_info_cache.end(); ++it_device_info) {
     for (media::VideoCaptureDevice::Names::iterator it =
              names_snapshot.begin();
          it != names_snapshot.end(); ++it) {
      if (it_device_info->name.id() == it->id()) {
        new_devices_info_cache.push_back(*it_device_info);
        names_snapshot.erase(it);
        break;
      }
    }
  }

  // Get the supported capture formats for the new devices in |names_snapshot|.
  for (media::VideoCaptureDevice::Names::const_iterator it =
           names_snapshot.begin();
       it != names_snapshot.end(); ++it) {
    media::VideoCaptureFormats supported_formats;
    DeviceInfo device_info(*it, media::VideoCaptureFormats());
    switch (artificial_device_source_for_testing_) {
      case DISABLED:
        media::VideoCaptureDevice::GetDeviceSupportedFormats(
            *it, &(device_info.supported_formats));
        break;
      case TEST_PATTERN:
        media::FakeVideoCaptureDevice::GetDeviceSupportedFormats(
            *it, &(device_info.supported_formats));
        break;
      case Y4M_FILE:
        media::FileVideoCaptureDevice::GetDeviceSupportedFormats(
            *it, &(device_info.supported_formats));
        break;
    }
    ConsolidateCaptureFormats(&device_info.supported_formats);
    new_devices_info_cache.push_back(device_info);
  }
  return new_devices_info_cache;
}

VideoCaptureManager::DeviceEntry*
VideoCaptureManager::GetDeviceEntryForMediaStreamDevice(
    const MediaStreamDevice& device_info) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  for (DeviceEntries::iterator it = devices_.begin();
       it != devices_.end(); ++it) {
    DeviceEntry* device = *it;
    if (device_info.type == device->stream_type &&
        device_info.id == device->id) {
      return device;
    }
  }
  return NULL;
}

VideoCaptureManager::DeviceEntry*
VideoCaptureManager::GetDeviceEntryForController(
    const VideoCaptureController* controller) {
  // Look up |controller| in |devices_|.
  for (DeviceEntries::iterator it = devices_.begin();
       it != devices_.end(); ++it) {
    if ((*it)->video_capture_controller.get() == controller) {
      return *it;
    }
  }
  return NULL;
}

void VideoCaptureManager::DestroyDeviceEntryIfNoClients(DeviceEntry* entry) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  // Removal of the last client stops the device.
  if (entry->video_capture_controller->GetClientCount() == 0) {
    DVLOG(1) << "VideoCaptureManager stopping device (type = "
             << entry->stream_type << ", id = " << entry->id << ")";

    // The DeviceEntry is removed from |devices_| immediately. The controller is
    // deleted immediately, and the device is freed asynchronously. After this
    // point, subsequent requests to open this same device ID will create a new
    // DeviceEntry, VideoCaptureController, and VideoCaptureDevice.
    devices_.erase(entry);
    entry->video_capture_controller.reset();
    device_task_runner_->PostTask(
        FROM_HERE,
        base::Bind(&VideoCaptureManager::DoStopDeviceOnDeviceThread, this,
                   base::Owned(entry)));
  }
}

VideoCaptureManager::DeviceEntry* VideoCaptureManager::GetOrCreateDeviceEntry(
    media::VideoCaptureSessionId capture_session_id) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  std::map<media::VideoCaptureSessionId, MediaStreamDevice>::iterator
      session_it = sessions_.find(capture_session_id);
  if (session_it == sessions_.end()) {
    return NULL;
  }
  const MediaStreamDevice& device_info = session_it->second;

  // Check if another session has already opened this device. If so, just
  // use that opened device.
  DeviceEntry* const existing_device =
      GetDeviceEntryForMediaStreamDevice(device_info);
  if (existing_device) {
    DCHECK_EQ(device_info.type, existing_device->stream_type);
    return existing_device;
  }

  scoped_ptr<VideoCaptureController> video_capture_controller(
      new VideoCaptureController());
  DeviceEntry* new_device = new DeviceEntry(device_info.type,
                                            device_info.id,
                                            video_capture_controller.Pass());
  devices_.insert(new_device);
  return new_device;
}

VideoCaptureManager::DeviceInfo* VideoCaptureManager::FindDeviceInfoById(
    const std::string& id,
    DeviceInfos& device_vector) {
  for (DeviceInfos::iterator it = device_vector.begin();
       it != device_vector.end(); ++it) {
    if (it->name.id() == id)
      return &(*it);
  }
  return NULL;
}

void VideoCaptureManager::SetDesktopCaptureWindowIdOnDeviceThread(
    DeviceEntry* entry,
    gfx::NativeViewId window_id) {
  DCHECK(IsOnDeviceThread());
  DCHECK(entry->stream_type == MEDIA_DESKTOP_VIDEO_CAPTURE);
#if defined(ENABLE_SCREEN_CAPTURE)
  DesktopCaptureDevice* device =
      static_cast<DesktopCaptureDevice*>(entry->video_capture_device.get());
  device->SetNotificationWindowId(window_id);
#endif
}

void VideoCaptureManager::SaveDesktopCaptureWindowIdOnDeviceThread(
    media::VideoCaptureSessionId session_id,
    gfx::NativeViewId window_id) {
  DCHECK(IsOnDeviceThread());
  DCHECK(notification_window_ids_.find(session_id) ==
         notification_window_ids_.end());
  notification_window_ids_[session_id] = window_id;
}

}  // namespace content