Cast: Add GetStats() extensions API.

chrome/renderer/media/cast_session_delegate.h

Index: chrome/renderer/media/cast_session_delegate.h
diff --git a/chrome/renderer/media/cast_session_delegate.h b/chrome/renderer/media/cast_session_delegate.h
index 9d08882474785b871b96905dfeba50d04fbdbd9a..863ab03394fc5adcd49498966b588eead05ece46 100644
--- a/chrome/renderer/media/cast_session_delegate.h
+++ b/chrome/renderer/media/cast_session_delegate.h
@@ -18,6 +18,7 @@
 #include "media/cast/cast_sender.h"
 
 namespace base {
+class DictionaryValue;
 class MessageLoopProxy;
 }  // namespace base
 
@@ -44,6 +45,7 @@ class CastSessionDelegate {
   typedef base::Callback<void(const scoped_refptr<media::cast::FrameInput>&)>
       FrameInputAvailableCallback;
   typedef base::Callback<void(scoped_ptr<std::string>)> EventLogsCallback;
+  typedef base::Callback<void(scoped_ptr<base::DictionaryValue>)> StatsCallback;
 
   CastSessionDelegate();
   virtual ~CastSessionDelegate();
@@ -62,6 +64,7 @@ class CastSessionDelegate {
 
   void ToggleLogging(bool is_audio, bool enable);
   void GetEventLogsAndReset(bool is_audio, const EventLogsCallback& callback);
+  void GetStatsAndReset(bool is_audio, const StatsCallback& callback);
 
  protected:
   // Callback with the result of the initialization.