root/content/browser/geolocation/location_arbitrator_impl.cc

DEFINITIONS

1. is_running_
2. DefaultNetworkProviderURL
3. OnPermissionGranted
4. StartProviders
5. DoStartProviders
6. StopProviders
7. OnAccessTokenStoresLoaded
8. RegisterProvider
9. LocationUpdateAvailable
10. NewAccessTokenStore
11. GetAccessTokenStore
12. NewNetworkLocationProvider
13. NewSystemLocationProvider
14. GetTimeNow
15. IsNewPositionBetter
16. HasPermissionBeenGranted

// 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/geolocation/location_arbitrator_impl.h"

#include <map>

#include "base/bind.h"
#include "base/bind_helpers.h"
#include "content/browser/geolocation/network_location_provider.h"
#include "content/public/browser/access_token_store.h"
#include "content/public/browser/content_browser_client.h"
#include "content/public/common/content_client.h"
#include "url/gurl.h"

namespace content {
namespace {

const char* kDefaultNetworkProviderUrl =
    "https://www.googleapis.com/geolocation/v1/geolocate";
}  // namespace

// To avoid oscillations, set this to twice the expected update interval of a
// a GPS-type location provider (in case it misses a beat) plus a little.
const int64 LocationArbitratorImpl::kFixStaleTimeoutMilliseconds =
    11 * base::Time::kMillisecondsPerSecond;

LocationArbitratorImpl::LocationArbitratorImpl(
    const LocationUpdateCallback& callback)
    : callback_(callback),
      provider_callback_(
          base::Bind(&LocationArbitratorImpl::LocationUpdateAvailable,
                     base::Unretained(this))),
      position_provider_(NULL),
      is_permission_granted_(false),
      is_running_(false) {
}

LocationArbitratorImpl::~LocationArbitratorImpl() {
}

GURL LocationArbitratorImpl::DefaultNetworkProviderURL() {
  return GURL(kDefaultNetworkProviderUrl);
}

void LocationArbitratorImpl::OnPermissionGranted() {
  is_permission_granted_ = true;
  for (ScopedVector<LocationProvider>::iterator i = providers_.begin();
      i != providers_.end(); ++i) {
    (*i)->OnPermissionGranted();
  }
}

void LocationArbitratorImpl::StartProviders(bool use_high_accuracy) {
  // Stash options as OnAccessTokenStoresLoaded has not yet been called.
  is_running_ = true;
  use_high_accuracy_ = use_high_accuracy;
  if (providers_.empty()) {
    DCHECK(DefaultNetworkProviderURL().is_valid());
    GetAccessTokenStore()->LoadAccessTokens(
        base::Bind(&LocationArbitratorImpl::OnAccessTokenStoresLoaded,
                   base::Unretained(this)));
  } else {
    DoStartProviders();
  }
}

void LocationArbitratorImpl::DoStartProviders() {
  for (ScopedVector<LocationProvider>::iterator i = providers_.begin();
       i != providers_.end(); ++i) {
    (*i)->StartProvider(use_high_accuracy_);
  }
}

void LocationArbitratorImpl::StopProviders() {
  // Reset the reference location state (provider+position)
  // so that future starts use fresh locations from
  // the newly constructed providers.
  position_provider_ = NULL;
  position_ = Geoposition();

  providers_.clear();
  is_running_ = false;
}

void LocationArbitratorImpl::OnAccessTokenStoresLoaded(
    AccessTokenStore::AccessTokenSet access_token_set,
    net::URLRequestContextGetter* context_getter) {
  if (!is_running_ || !providers_.empty()) {
    // A second StartProviders() call may have arrived before the first
    // completed.
    return;
  }
  // If there are no access tokens, boot strap it with the default server URL.
  if (access_token_set.empty())
    access_token_set[DefaultNetworkProviderURL()];
  for (AccessTokenStore::AccessTokenSet::iterator i =
           access_token_set.begin();
      i != access_token_set.end(); ++i) {
    RegisterProvider(
        NewNetworkLocationProvider(
            GetAccessTokenStore(), context_getter,
            i->first, i->second));
  }

  LocationProvider* provider =
      GetContentClient()->browser()->OverrideSystemLocationProvider();
  if (!provider)
    provider = NewSystemLocationProvider();
  RegisterProvider(provider);
  DoStartProviders();
}

void LocationArbitratorImpl::RegisterProvider(
    LocationProvider* provider) {
  if (!provider)
    return;
  provider->SetUpdateCallback(provider_callback_);
  if (is_permission_granted_)
    provider->OnPermissionGranted();
  providers_.push_back(provider);
}

void LocationArbitratorImpl::LocationUpdateAvailable(
    const LocationProvider* provider,
    const Geoposition& new_position) {
  DCHECK(new_position.Validate() ||
         new_position.error_code != Geoposition::ERROR_CODE_NONE);
  if (!IsNewPositionBetter(position_, new_position,
                           provider == position_provider_))
    return;
  position_provider_ = provider;
  position_ = new_position;
  callback_.Run(position_);
}

AccessTokenStore* LocationArbitratorImpl::NewAccessTokenStore() {
  return GetContentClient()->browser()->CreateAccessTokenStore();
}

AccessTokenStore* LocationArbitratorImpl::GetAccessTokenStore() {
  if (!access_token_store_.get())
    access_token_store_ = NewAccessTokenStore();
  return access_token_store_.get();
}

LocationProvider* LocationArbitratorImpl::NewNetworkLocationProvider(
    AccessTokenStore* access_token_store,
    net::URLRequestContextGetter* context,
    const GURL& url,
    const base::string16& access_token) {
#if defined(OS_ANDROID)
  // Android uses its own SystemLocationProvider.
  return NULL;
#else
  return new NetworkLocationProvider(access_token_store, context, url,
                                     access_token);
#endif
}

LocationProvider* LocationArbitratorImpl::NewSystemLocationProvider() {
#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX)
  return NULL;
#else
  return content::NewSystemLocationProvider();
#endif
}

base::Time LocationArbitratorImpl::GetTimeNow() const {
  return base::Time::Now();
}

bool LocationArbitratorImpl::IsNewPositionBetter(
    const Geoposition& old_position, const Geoposition& new_position,
    bool from_same_provider) const {
  // Updates location_info if it's better than what we currently have,
  // or if it's a newer update from the same provider.
  if (!old_position.Validate()) {
    // Older location wasn't locked.
    return true;
  }
  if (new_position.Validate()) {
    // New location is locked, let's check if it's any better.
    if (old_position.accuracy >= new_position.accuracy) {
      // Accuracy is better.
      return true;
    } else if (from_same_provider) {
      // Same provider, fresher location.
      return true;
    } else if ((GetTimeNow() - old_position.timestamp).InMilliseconds() >
               kFixStaleTimeoutMilliseconds) {
      // Existing fix is stale.
      return true;
    }
  }
  return false;
}

bool LocationArbitratorImpl::HasPermissionBeenGranted() const {
  return is_permission_granted_;
}

}  // namespace content