Convert media constants to constexpr.

media/base/audio_discard_helper.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_BASE_AUDIO_DISCARD_HELPER_H_
 #define MEDIA_BASE_AUDIO_DISCARD_HELPER_H_
 
 #include <stddef.h>
 
 #include "base/macros.h"
@@ skipping 42 matching lines @@
   //
   // If AudioDiscardHelper is not initialized() the timestamp of the first
   // |encoded_buffer| will be used as the basis for all future timestamps set on
   // |decoded_buffer|s.  If the first buffer has a negative timestamp it will be
   // clamped to zero.
   bool ProcessBuffers(const scoped_refptr<DecoderBuffer>& encoded_buffer,
                       const scoped_refptr<AudioBuffer>& decoded_buffer);
 
   // Whether any buffers have been processed.
   bool initialized() const {
-    return timestamp_helper_.base_timestamp() != kNoTimestamp();
+    return timestamp_helper_.base_timestamp() != kNoTimestamp;
   }
 
  private:
   // The sample rate of the decoded audio samples.  Used by TimeDeltaToFrames()
   // and the timestamp helper.
   const int sample_rate_;
 
   // Some codecs output extra samples during the first decode.  In order to trim
   // DiscardPadding correctly the helper must know the offset into the decoded
   // buffers at which real samples start.
@@ skipping 25 matching lines @@
   // from the next buffer.  The index at which to start discarding is calculated
   // by subtracting |delayed_end_discard_| from |decoder_delay_|.
   size_t delayed_end_discard_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(AudioDiscardHelper);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_DISCARD_HELPER_H_