Add IPC to query capabilities of video input devices.

content/browser/frame_host/render_frame_host_delegate.h

Index: content/browser/frame_host/render_frame_host_delegate.h
diff --git a/content/browser/frame_host/render_frame_host_delegate.h b/content/browser/frame_host/render_frame_host_delegate.h
index 4f3178036cda45d6dee1f0b9e6f4d0bbd2672ad9..77a62aac7bae4ac9e79fcfaa7e1c1e4136335836 100644
--- a/content/browser/frame_host/render_frame_host_delegate.h
+++ b/content/browser/frame_host/render_frame_host_delegate.h
@@ -155,9 +155,15 @@ class CONTENT_EXPORT RenderFrameHostDelegate {
   // Checks if we have permission to access the microphone or camera. Note that
   // this does not query the user. |type| must be MEDIA_DEVICE_AUDIO_CAPTURE
   // or MEDIA_DEVICE_VIDEO_CAPTURE.
+  // TODO(guidou): use url::Origin for |security_origin|. See crbug.com/683115.
   virtual bool CheckMediaAccessPermission(const GURL& security_origin,
                                           MediaStreamType type);
 
+  // Returns the ID of the default device for the given media device |type|.
+  // If the returned value is an empty string, it means that there is no
+  // default device for the given |type|.
+  virtual std::string GetDefaultMediaDeviceID(MediaStreamType type);
+
   // Get the accessibility mode for the WebContents that owns this frame.
   virtual AccessibilityMode GetAccessibilityMode() const;