Convert media constants to constexpr.

media/formats/webm/webm_tracks_parser.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 MEDIA_FORMATS_WEBM_WEBM_TRACKS_PARSER_H_
 #define MEDIA_FORMATS_WEBM_WEBM_TRACKS_PARSER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 30 matching lines @@
   // Returns 0 if more data is needed.
   // Returns the number of bytes parsed on success.
   int Parse(const uint8_t* buf, int size);
 
   int64_t audio_track_num() const { return audio_track_num_; }
   int64_t video_track_num() const { return video_track_num_; }
 
   // If TrackEntry DefaultDuration field existed for the associated audio or
   // video track, returns that value converted from ns to base::TimeDelta with
   // precision not greater than |timecode_scale_in_us|. Defaults to
-  // kNoTimestamp().
+  // kNoTimestamp.
   base::TimeDelta GetAudioDefaultDuration(
       const double timecode_scale_in_us) const;
   base::TimeDelta GetVideoDefaultDuration(
       const double timecode_scale_in_us) const;
 
   const std::set<int64_t>& ignored_tracks() const { return ignored_tracks_; }
 
   const std::string& audio_encryption_key_id() const {
     return audio_encryption_key_id_;
   }
@@ skipping 76 matching lines @@
   int detected_video_track_count_;
   int detected_text_track_count_;
   std::unique_ptr<MediaTracks> media_tracks_;
 
   DISALLOW_COPY_AND_ASSIGN(WebMTracksParser);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FORMATS_WEBM_WEBM_TRACKS_PARSER_H_