Cast: Fix two video freezing problems

media/cast/transport/rtp_sender/rtp_sender.h

Index: media/cast/transport/rtp_sender/rtp_sender.h
diff --git a/media/cast/transport/rtp_sender/rtp_sender.h b/media/cast/transport/rtp_sender/rtp_sender.h
index 171ffe26314ea6ac92a79d359cc5685ed39e9b8d..3fe018222fbf0c84d0e35a04f9c10dabf8a3ad3e 100644
--- a/media/cast/transport/rtp_sender/rtp_sender.h
+++ b/media/cast/transport/rtp_sender/rtp_sender.h
@@ -41,12 +41,12 @@ class RtpSender {
   ~RtpSender();
 
   // Initialize audio stack. Audio must be initialized prior to sending encoded
-  // audio frames.
-  void InitializeAudio(const CastTransportAudioConfig& config);
+  // audio frames. Returns false if configuration is invalid.
+  bool InitializeAudio(const CastTransportAudioConfig& config);
 
   // Initialize video stack. Video must be initialized prior to sending encoded
-  // video frames.
-  void InitializeVideo(const CastTransportVideoConfig& config);
+  // video frames. Returns false if configuration is invalid.
+  bool InitializeVideo(const CastTransportVideoConfig& config);
 
   // The video_frame objects ownership is handled by the main cast thread.
   void IncomingEncodedVideoFrame(const EncodedVideoFrame* video_frame,