support video device enumeration from renderer process.

content/renderer/media/media_stream_dispatcher.h

Index: content/renderer/media/media_stream_dispatcher.h
===================================================================
--- content/renderer/media/media_stream_dispatcher.h	(revision 109718)
+++ content/renderer/media/media_stream_dispatcher.h	(working copy)
@@ -40,6 +40,20 @@
   // Stop a started stream. Label is the label provided in OnStreamGenerated.
   void StopStream(const std::string& label);
 
+  // Request to enumerate video devices.
+  void EnumerateVideoDevices(int request_id,
+                             MediaStreamDispatcherEventHandler* event_handler,
+                             const std::string& security_origin);
+
+  // Request to open a video device.
+  void OpenVideoDevice(int request_id,
+                       MediaStreamDispatcherEventHandler* event_handler,
+                       const std::string& device_id,
+                       const std::string& security_origin);
+
+  // Close a started video device. |label| is provided in OnVideoDeviceOpened.
+  void CloseVideoDevice(const std::string& label);
+
   // Check if the label is a valid stream.
   bool IsStream(const std::string& label);
   // Get the video session_id given a label. The label identifies a stream.
@@ -49,7 +63,8 @@
   int audio_session_id(const std::string& label, int index);
 
  private:
-  FRIEND_TEST_ALL_PREFIXES(MediaStreamDispatcherTest, Basic);
+  FRIEND_TEST_ALL_PREFIXES(MediaStreamDispatcherTest, BasicStream);
+  FRIEND_TEST_ALL_PREFIXES(MediaStreamDispatcherTest, BasicVideoDevice);
   FRIEND_TEST_ALL_PREFIXES(MediaStreamDispatcherTest, TestFailure);
 
   struct Request;
@@ -68,6 +83,15 @@
   void OnStreamGenerationFailed(int request_id);
   void OnVideoDeviceFailed(const std::string& label, int index);
   void OnAudioDeviceFailed(const std::string& label, int index);
+  void OnVideoDevicesEnumerated(
+      int request_id,
+      const media_stream::StreamDeviceInfoArray& device_array);
+  void OnVideoDevicesEnumerationFailed(int request_id);
+  void OnVideoDeviceOpened(
+      int request_id,
+      const std::string& label,
+      const media_stream::StreamDeviceInfo& device_info);
+  void OnVideoDeviceOpenFailed(int request_id);
 
   int next_ipc_id_;
   typedef std::map<std::string, Stream> LabelStreamMap;