Add support for device-change notifications to MediaStreamDispatcher and MediaStreamDispatcherHost

content/renderer/media/media_stream_dispatcher.h

 // 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.
 
 #ifndef CONTENT_RENDERER_MEDIA_MEDIA_STREAM_DISPATCHER_H_
 #define CONTENT_RENDERER_MEDIA_MEDIA_STREAM_DISPATCHER_H_
 
 #include <list>
 #include <map>
 #include <memory>
 #include <string>
+#include <vector>
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "content/common/content_export.h"
 #include "content/common/media/media_stream_options.h"
 #include "content/public/renderer/render_frame_observer.h"
 #include "content/renderer/media/media_stream_dispatcher_eventhandler.h"
 
@@ skipping 49 matching lines @@
       const GURL& security_origin);
 
   // Cancel the request to open a device.
   virtual void CancelOpenDevice(
       int request_id,
       const base::WeakPtr<MediaStreamDispatcherEventHandler>& event_handler);
 
   // Close a started device. |label| is provided in OnDeviceOpened.
   void CloseDevice(const std::string& label);
 
+  // Register and unregister event handlers for device-change notifications.
+  // It is an error to try to subscribe a handler that is already subscribed or
+  // to cancel the subscription of a handler that is not subscribed. Also,
+  // each subscribed handler must make sure to invoke
+  // CancelDeviceChangeNotifications() before the handler is destroyed.
+  void SubscribeToDeviceChangeNotifications(
+      const base::WeakPtr<MediaStreamDispatcherEventHandler>& event_handler,
+      const GURL& security_origin);
+  void CancelDeviceChangeNotifications(
+      const base::WeakPtr<MediaStreamDispatcherEventHandler>& event_handler);
+
   // Check if the label is a valid stream.
   virtual bool IsStream(const std::string& label);
   // Get the video session_id given a label. The label identifies a stream.
   // index is the index in the video_device_array of the stream.
   virtual int video_session_id(const std::string& label, int index);
   // Returns an audio session_id given a label and an index.
   virtual int audio_session_id(const std::string& label, int index);
 
  protected:
   int GetNextIpcIdForTest() { return next_ipc_id_; }
@@ skipping 26 matching lines @@
   void OnDeviceStopped(const std::string& label,
                        const StreamDeviceInfo& device_info);
   void OnDevicesEnumerated(
       int request_id,
       const StreamDeviceInfoArray& device_array);
   void OnDeviceOpened(
       int request_id,
       const std::string& label,
       const StreamDeviceInfo& device_info);
   void OnDeviceOpenFailed(int request_id);
+  void OnDevicesChanged();
 
   // Used for DCHECKs so methods calls won't execute in the wrong thread.
   base::ThreadChecker thread_checker_;
 
   int next_ipc_id_;
   typedef std::map<std::string, Stream> LabelStreamMap;
   LabelStreamMap label_stream_map_;
 
   // List of calls made to the browser process that have not yet completed or
   // been canceled.
   typedef std::list<Request> RequestList;
   RequestList requests_;
 
+  std::vector<base::WeakPtr<MediaStreamDispatcherEventHandler>>
+      device_change_subscribers_;
+
   DISALLOW_COPY_AND_ASSIGN(MediaStreamDispatcher);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_MEDIA_STREAM_DISPATCHER_H_