support video device enumeration from renderer process.

content/browser/renderer_host/media/media_stream_requester.h

Index: content/browser/renderer_host/media/media_stream_requester.h
===================================================================
--- content/browser/renderer_host/media/media_stream_requester.h	(revision 118766)
+++ content/browser/renderer_host/media/media_stream_requester.h	(working copy)
@@ -30,6 +30,17 @@
   // an error.
   virtual void VideoDeviceFailed(const std::string& label, int index) = 0;
 
+  // Called as a reply of a successful call to EnumerateDevices.
+  virtual void DevicesEnumerated(const std::string& label,
+                                 const StreamDeviceInfoArray& devices) = 0;
+  // Called if EnumerateDevices failed.
+  virtual void DevicesEnumerationFailed(const std::string& label) = 0;
+  // Called as a reply of a successful call to OpenDevice.
+  virtual void DeviceOpened(const std::string& label,
+                            const StreamDeviceInfo& device_info) = 0;
+  // Called if OpenDevice failed.
+  virtual void DeviceOpenFailed(const std::string& label) = 0;
+
  protected:
   virtual ~MediaStreamRequester() {
   }