Convert media constants to constexpr.

chromecast/media/cma/base/buffering_state.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROMECAST_MEDIA_CMA_BASE_BUFFERING_STATE_H_
 #define CHROMECAST_MEDIA_CMA_BASE_BUFFERING_STATE_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 101 matching lines @@
   // Callback invoked each time there is a change of state.
   base::Closure state_changed_cb_;
 
   // Callback invoked to adjust the high buffer level.
   HighLevelBufferCB high_level_buffer_cb_;
 
   // State.
   State state_;
 
   // Playback media time.
-  // Equal to kNoTimestamp() when not known.
+  // Equal to kNoTimestamp when not known.
   base::TimeDelta media_time_;
 
   // Maximum rendering media time.
   // This corresponds to the timestamp of the last frame sent to the hardware
   // decoder/renderer.
   base::TimeDelta max_rendering_time_;
 
   // Buffered media time.
-  // Equal to kNoTimestamp() when not known.
+  // Equal to kNoTimestamp when not known.
   base::TimeDelta buffered_time_;
 
   DISALLOW_COPY_AND_ASSIGN(BufferingState);
 };
 
 }  // namespace media
 }  // namespace chromecast
 
 #endif  // CHROMECAST_MEDIA_CMA_BASE_BUFFERING_STATE_H_