media::SeekableBuffer should use kNoTimestamp() instead of zero.

media/base/seekable_buffer.cc

 // Copyright (c) 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/base/seekable_buffer.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "media/base/data_buffer.h"
@@ skipping 43 matching lines @@
     current_buffer_offset = 0;
   }
   if (current_buffer == buffers_.end())
     return false;
   *data = (*current_buffer)->GetData() + current_buffer_offset;
   *size = (*current_buffer)->GetDataSize() - current_buffer_offset;
   return true;
 }
 
 bool SeekableBuffer::Append(Buffer* buffer_in) {
-  if (buffers_.empty() && buffer_in->GetTimestamp().InMicroseconds() > 0) {
+  if (buffers_.empty() && buffer_in->GetTimestamp() != kNoTimestamp()) {
     current_time_ = buffer_in->GetTimestamp();
   }
 
   // Since the forward capacity is only used to check the criteria for buffer
   // full, we always append data to the buffer.
   buffers_.push_back(scoped_refptr<Buffer>(buffer_in));
 
   // After we have written the first buffer, update |current_buffer_| to point
   // to it.
   if (current_buffer_ == buffers_.end()) {
@@ skipping 185 matching lines @@
     UpdateCurrentTime(current_buffer_, current_buffer_offset_);
     EvictBackwardBuffers();
   }
 
   return taken;
 }
 
 void SeekableBuffer::UpdateCurrentTime(BufferQueue::iterator buffer,
                                        int offset) {
   // Garbage values are unavoidable, so this check will remain.
-  if (buffer != buffers_.end() &&
-      (*buffer)->GetTimestamp().InMicroseconds() > 0) {
+  if (buffer != buffers_.end() && (*buffer)->GetTimestamp() != kNoTimestamp()) {
     int64 time_offset = ((*buffer)->GetDuration().InMicroseconds() *
                          offset) / (*buffer)->GetDataSize();
 
     current_time_ = (*buffer)->GetTimestamp() +
         base::TimeDelta::FromMicroseconds(time_offset);
   }
 }
 
 }  // namespace media