Convert media constants to constexpr.

media/filters/opus_audio_decoder.cc

 // Copyright 2012 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.
 
 #include "media/filters/opus_audio_decoder.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <cmath>
@@ skipping 184 matching lines @@
 
   // Libopus does not buffer output. Decoding is complete when an end of stream
   // input buffer is received.
   if (input->end_of_stream()) {
     decode_cb.Run(DecodeStatus::OK);
     return;
   }
 
   // Make sure we are notified if http://crbug.com/49709 returns.  Issue also
   // occurs with some damaged files.
-  if (input->timestamp() == kNoTimestamp()) {
+  if (input->timestamp() == kNoTimestamp) {
     DLOG(ERROR) << "Received a buffer without timestamps!";
     decode_cb.Run(DecodeStatus::DECODE_ERROR);
     return;
   }
 
   scoped_refptr<AudioBuffer> output_buffer;
 
   if (!Decode(input, &output_buffer)) {
     decode_cb.Run(DecodeStatus::DECODE_ERROR);
     return;
@@ skipping 143 matching lines @@
     output_buffer->get()->TrimEnd(trim_frames);
 
   // Handles discards and timestamping.  Discard the buffer if more data needed.
   if (!discard_helper_->ProcessBuffers(input, *output_buffer))
     *output_buffer = nullptr;
 
   return true;
 }
 
 }  // namespace media