Add a mechanism to pause and resume geolocation requests.

content/browser/geolocation/geolocation_dispatcher_host.cc

Index: content/browser/geolocation/geolocation_dispatcher_host.cc
diff --git a/content/browser/geolocation/geolocation_dispatcher_host.cc b/content/browser/geolocation/geolocation_dispatcher_host.cc
index 96071c748f5e72d5e00dce006be77a7ee903e730..ac50a40d83621a05d4abd936a3078a186a9d9980 100644
--- a/content/browser/geolocation/geolocation_dispatcher_host.cc
+++ b/content/browser/geolocation/geolocation_dispatcher_host.cc
@@ -66,26 +66,41 @@ class GeolocationDispatcherHostImpl : public GeolocationDispatcherHost {
                                  const GURL& requesting_frame);
   void OnStartUpdating(int render_view_id,
                        const GURL& requesting_frame,
-      bool enable_high_accuracy);
+                       bool enable_high_accuracy);
   void OnStopUpdating(int render_view_id);
 
+
+  virtual void PauseOrResume(int render_view_id, bool should_pause) OVERRIDE;
+
   // Updates the |geolocation_provider_| with the currently required update
-  // options, based on |renderer_high_accuracy_|.
-  void RefreshHighAccuracy();
+  // options.
+  void RefreshGeolocationOptions();
 
   void OnLocationUpdate(const Geoposition& position);
 
   int render_process_id_;
   scoped_refptr<GeolocationPermissionContext> geolocation_permission_context_;
 
-  // Iterated when sending location updates to renderer processes. The fan out
-  // to individual bridge IDs happens renderer side, in order to minimize
-  // context switches.
+  struct RendererGeolocationOptions {
+    bool high_accuracy;
+    bool is_paused;
+  };
+
+  // Used to keep track of the renderers in this process that are using
+  // geolocation and the options associated with them. The map is iterated
+  // when a location update is available and the fan out to individual bridge
+  // IDs happens renderer side, in order to minimize context switches.
   // Only used on the IO thread.
-  std::set<int> geolocation_renderer_ids_;
-  // Maps renderer_id to whether high accuracy is requested for this particular
-  // bridge.
-  std::map<int, bool> renderer_high_accuracy_;
+  std::map<int, RendererGeolocationOptions> geolocation_renderers_;
+
+  // Used by Android WebView to support that case that a renderer is in the
+  // 'paused' state but not yet using geolocation. If the renderer does start
+  // using geolocation while paused, we move from this set into
+  // |geolocation_renderers_|. If the renderer doesn't end up wanting to use
+  // geolocation while 'paused' then we remove from this set. A renderer id
+  // can exist only in this set or |geolocation_renderers_|, never both.
+  std::set<int> pending_paused_geolocation_renderers_;
+
   // Only set whilst we are registered with the geolocation provider.
   GeolocationProviderImpl* geolocation_provider_;
 
@@ -108,8 +123,14 @@ GeolocationDispatcherHostImpl::GeolocationDispatcherHostImpl(
 }
 
 GeolocationDispatcherHostImpl::~GeolocationDispatcherHostImpl() {
-  if (geolocation_provider_)
-    geolocation_provider_->RemoveLocationUpdateCallback(callback_);
+  if (geolocation_provider_) {
+    BrowserThread::PostTask(
+        BrowserThread::IO, FROM_HERE,
+        base::Bind(
+            base::IgnoreResult(
+                &GeolocationProvider::RemoveLocationUpdateCallback),
+            base::Unretained(geolocation_provider_), callback_));
+  }
 }
 
 bool GeolocationDispatcherHostImpl::OnMessageReceived(
@@ -132,9 +153,11 @@ bool GeolocationDispatcherHostImpl::OnMessageReceived(
 void GeolocationDispatcherHostImpl::OnLocationUpdate(
     const Geoposition& geoposition) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  for (std::set<int>::iterator it = geolocation_renderer_ids_.begin();
-       it != geolocation_renderer_ids_.end(); ++it) {
-    Send(new GeolocationMsg_PositionUpdated(*it, geoposition));
+  for (std::map<int, RendererGeolocationOptions>::iterator it =
+       geolocation_renderers_.begin();
+       it != geolocation_renderers_.end(); ++it) {
+    if (!(it->second.is_paused))
+      Send(new GeolocationMsg_PositionUpdated(it->first, geoposition));
   }
 }
 
@@ -188,47 +211,81 @@ void GeolocationDispatcherHostImpl::OnStartUpdating(
   UMA_HISTOGRAM_BOOLEAN(
       "Geolocation.GeolocationDispatcherHostImpl.EnableHighAccuracy",
       enable_high_accuracy);
-  if (!geolocation_renderer_ids_.count(render_view_id))
-    geolocation_renderer_ids_.insert(render_view_id);
 
-  renderer_high_accuracy_[render_view_id] = enable_high_accuracy;
-  RefreshHighAccuracy();
+  std::map<int, RendererGeolocationOptions>::iterator it =
+            geolocation_renderers_.find(render_view_id);
+  if (it == geolocation_renderers_.end()) {
+    bool should_start_paused = false;
+    if (pending_paused_geolocation_renderers_.erase(render_view_id) == 1) {
+      should_start_paused = true;
+    }
+    RendererGeolocationOptions opts = {
+      enable_high_accuracy,
+      should_start_paused
+    };
+    geolocation_renderers_[render_view_id] = opts;
+  } else {
+    it->second.high_accuracy = enable_high_accuracy;
+  }
+  RefreshGeolocationOptions();
 }
 
 void GeolocationDispatcherHostImpl::OnStopUpdating(int render_view_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   DVLOG(1) << __FUNCTION__ << " " << render_process_id_ << ":"
            << render_view_id;
-  if (renderer_high_accuracy_.erase(render_view_id))
-    RefreshHighAccuracy();
-
-  DCHECK_EQ(1U, geolocation_renderer_ids_.count(render_view_id));
-  geolocation_renderer_ids_.erase(render_view_id);
+  DCHECK_EQ(1U, geolocation_renderers_.count(render_view_id));
+  geolocation_renderers_.erase(render_view_id);
+  RefreshGeolocationOptions();
 }
 
-void GeolocationDispatcherHostImpl::RefreshHighAccuracy() {
+void GeolocationDispatcherHostImpl::PauseOrResume(int render_view_id,
+                                                  bool should_pause) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  if (renderer_high_accuracy_.empty()) {
-    if (geolocation_provider_) {
-      geolocation_provider_->RemoveLocationUpdateCallback(callback_);
-      geolocation_provider_ = NULL;
+  std::map<int, RendererGeolocationOptions>::iterator it =
+      geolocation_renderers_.find(render_view_id);
+  if (it == geolocation_renderers_.end()) {
+    // This renderer is not using geolocation yet, but if it does before
+    // we get a call to resume, we should start it up in the paused state.
+    if (should_pause) {
+      pending_paused_geolocation_renderers_.insert(render_view_id);
+    } else {
+      pending_paused_geolocation_renderers_.erase(render_view_id);
     }
   } else {
+    RendererGeolocationOptions* opts = &(it->second);
+    if (opts->is_paused != should_pause)
+      opts->is_paused = should_pause;
+    RefreshGeolocationOptions();
+  }
+}
+
+void GeolocationDispatcherHostImpl::RefreshGeolocationOptions() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  bool needs_updates = false;
+  bool use_high_accuracy = false;
+  std::map<int, RendererGeolocationOptions>::const_iterator i =
+      geolocation_renderers_.begin();
+  for (; i != geolocation_renderers_.end(); ++i) {
+    needs_updates |= !(i->second.is_paused);
+    use_high_accuracy |= i->second.high_accuracy;
+    if (needs_updates && use_high_accuracy)
+      break;
+  }
+  if (needs_updates) {
     if (!geolocation_provider_)
       geolocation_provider_ = GeolocationProviderImpl::GetInstance();
     // Re-add to re-establish our options, in case they changed.
-    bool use_high_accuracy = false;
-    std::map<int, bool>::iterator i = renderer_high_accuracy_.begin();
-    for (; i != renderer_high_accuracy_.end(); ++i) {
-      if (i->second) {
-        use_high_accuracy = true;
-        break;
-      }
-    }
     geolocation_provider_->AddLocationUpdateCallback(
         callback_, use_high_accuracy);
+  } else {
+    if (geolocation_provider_)
+      geolocation_provider_->RemoveLocationUpdateCallback(callback_);
+    geolocation_provider_ = NULL;
   }
 }
+
 }  // namespace