Allow shaped-desktop hosts to send shape only when it changes.

remoting/client/plugin/pepper_video_renderer.h

Index: remoting/client/plugin/pepper_video_renderer.h
diff --git a/remoting/client/plugin/pepper_video_renderer.h b/remoting/client/plugin/pepper_video_renderer.h
index 86713a56dd00ab7bbede6bb5391178747a95fb01..bc26bc03c0ae50bc2475b16897713a36434a43a2 100644
--- a/remoting/client/plugin/pepper_video_renderer.h
+++ b/remoting/client/plugin/pepper_video_renderer.h
@@ -40,8 +40,9 @@ class PepperVideoRenderer : public VideoRenderer {
     virtual void OnVideoSize(const webrtc::DesktopSize& size,
                              const webrtc::DesktopVector& dpi) = 0;
 
-    // Called when desktop shape changes.
-    virtual void OnVideoShape(const webrtc::DesktopRegion& shape) = 0;
+    // Called when desktop shape changes. |shape| should be NULL if frames are
+    // un-shaped.
+    virtual void OnVideoShape(const webrtc::DesktopRegion* shape) = 0;
 
     // Called with each frame's updated region, if EnableDebugDirtyRegion(true)
     // was called.