Convert media constants to constexpr.

media/base/android/media_statistics.h

 // Copyright 2015 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 MEDIA_BASE_ANDROID_MEDIA_STATISTICS_H_
 #define MEDIA_BASE_ANDROID_MEDIA_STATISTICS_H_
 
 #include <stdint.h>
 #include "base/time/time.h"
 #include "media/base/demuxer_stream.h"
@@ skipping 59 matching lines @@
   void AddStarvation() { ++num_starvations_; }
 
  private:
   // Resets the data to the initial state.
   void Clear();
 
   // Calculates relative data based on total frame numbers and reports it and
   // the duration to UMA.
   void Report(base::TimeDelta duration);
 
-  base::TimeDelta start_time_ = kNoTimestamp();
+  base::TimeDelta start_time_ = kNoTimestamp;
   FrameStatistics audio_frame_stats_;
   FrameStatistics video_frame_stats_;
   uint32_t num_starvations_ = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_ANDROID_MEDIA_STATISTICS_H_