support video device enumeration from renderer process.

content/renderer/media/media_stream_dispatcher_eventhandler.h

Index: content/renderer/media/media_stream_dispatcher_eventhandler.h
===================================================================
--- content/renderer/media/media_stream_dispatcher_eventhandler.h	(revision 118766)
+++ content/renderer/media/media_stream_dispatcher_eventhandler.h	(working copy)
@@ -33,6 +33,23 @@
   virtual void OnAudioDeviceFailed(const std::string& label,
                                    int index) = 0;
 
+  // A new list of devices have been enumerated.
+  virtual void OnDevicesEnumerated(
+      int request_id,
+      const media_stream::StreamDeviceInfoArray& device_array) = 0;
+
+  // Failed to enumerate devices.
+  virtual void OnDevicesEnumerationFailed(int request_id) = 0;
+
+  // A device has been opened.
+  virtual void OnDeviceOpened(
+      int request_id,
+      const std::string& label,
+      const media_stream::StreamDeviceInfo& device_info) = 0;
+
+  // Failed to open the device.
+  virtual void OnDeviceOpenFailed(int request_id) = 0;
+
  protected:
   virtual ~MediaStreamDispatcherEventHandler();
 };