Propagate media play/pause to WebContentsObserver for Chromecast metrics

content/public/browser/web_contents_observer.h

Index: content/public/browser/web_contents_observer.h
diff --git a/content/public/browser/web_contents_observer.h b/content/public/browser/web_contents_observer.h
index a176d18cbb06363238243250980f44e7083962b3..737b16a2384a571aa20bf0ef7cf4fa2c19021b3b 100644
--- a/content/public/browser/web_contents_observer.h
+++ b/content/public/browser/web_contents_observer.h
@@ -343,6 +343,12 @@ class CONTENT_EXPORT WebContentsObserver : public IPC::Listener,
   // Invoked when theme color is changed to |theme_color|.
   virtual void DidChangeThemeColor(SkColor theme_color) {}
 
+  // Invoked when media is playing.
+  virtual void MediaStartedPlaying() {}
+
+  // Invoked when media is paused.
+  virtual void MediaPaused() {}
+
   // Invoked if an IPC message is coming from a specific RenderFrameHost.
   virtual bool OnMessageReceived(const IPC::Message& message,
                                  RenderFrameHost* render_frame_host);