Add support for device-change notifications to MediaStreamDispatcher and MediaStreamDispatcherHost

content/renderer/media/media_stream_dispatcher.cc

Index: content/renderer/media/media_stream_dispatcher.cc
diff --git a/content/renderer/media/media_stream_dispatcher.cc b/content/renderer/media/media_stream_dispatcher.cc
index 786196f7d12a00fae3f778161d1c81894887cd18..e19b1e03b8021219aeb2ebfe230f78046813ad1d 100644
--- a/content/renderer/media/media_stream_dispatcher.cc
+++ b/content/renderer/media/media_stream_dispatcher.cc
@@ -68,7 +68,9 @@ MediaStreamDispatcher::MediaStreamDispatcher(RenderFrame* render_frame)
       next_ipc_id_(0) {
 }
 
-MediaStreamDispatcher::~MediaStreamDispatcher() {}
+MediaStreamDispatcher::~MediaStreamDispatcher() {
+  DCHECK(device_change_subscribers_.empty());
+}
 
 void MediaStreamDispatcher::GenerateStream(
     int request_id,
@@ -209,6 +211,43 @@ void MediaStreamDispatcher::CloseDevice(const std::string& label) {
   Send(new MediaStreamHostMsg_CloseDevice(routing_id(), label));
 }
 
+void MediaStreamDispatcher::SubscribeToDeviceChangeNotifications(
+    const base::WeakPtr<MediaStreamDispatcherEventHandler>& event_handler,
+    const url::Origin& security_origin) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(std::find_if(
+             device_change_subscribers_.begin(),
+             device_change_subscribers_.end(),
+             [&event_handler](
+                 const base::WeakPtr<MediaStreamDispatcherEventHandler>& item) {
+               return event_handler.get() == item.get();
+             }) == device_change_subscribers_.end());
+  DVLOG(1) << "MediaStreamDispatcher::SubscribeToDeviceChangeNotifications";
+
+  if (device_change_subscribers_.empty()) {
+    Send(new MediaStreamHostMsg_SubscribeToDeviceChangeNotifications(
+        routing_id(), security_origin));
+  }
+  device_change_subscribers_.push_back(event_handler);
+}
+
+void MediaStreamDispatcher::CancelDeviceChangeNotifications(
+    const base::WeakPtr<MediaStreamDispatcherEventHandler>& event_handler) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DVLOG(1) << "MediaStreamDispatcher::SubscribeToDeviceChangeNotifications";
+  auto it = std::find_if(
+      device_change_subscribers_.begin(), device_change_subscribers_.end(),
+      [&event_handler](
+          const base::WeakPtr<MediaStreamDispatcherEventHandler>& item) {
+        return event_handler.get() == item.get();
+      });
+  CHECK(it != device_change_subscribers_.end());
+  device_change_subscribers_.erase(it);
+
+  if (device_change_subscribers_.empty())
+    Send(new MediaStreamHostMsg_CancelDeviceChangeNotifications(routing_id()));
+}
+
 void MediaStreamDispatcher::OnDestruct() {
   // Do not self-destruct. UserMediaClientImpl owns |this|.
 }
@@ -237,6 +276,7 @@ bool MediaStreamDispatcher::OnMessageReceived(const IPC::Message& message) {
                         OnDeviceOpened)
     IPC_MESSAGE_HANDLER(MediaStreamMsg_DeviceOpenFailed,
                         OnDeviceOpenFailed)
+    IPC_MESSAGE_HANDLER(MediaStreamMsg_DevicesChanged, OnDevicesChanged)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
@@ -378,6 +418,14 @@ void MediaStreamDispatcher::OnDeviceOpenFailed(int request_id) {
   }
 }
 
+void MediaStreamDispatcher::OnDevicesChanged() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  for (auto event_handler : device_change_subscribers_) {
+    DCHECK(event_handler);
+    event_handler->OnDevicesChanged();
+  }
+}
+
 int MediaStreamDispatcher::audio_session_id(const std::string& label,
                                             int index) {
   DCHECK(thread_checker_.CalledOnValidThread());