Add offset support to BitstreamBuffer.

media/base/bitstream_buffer.cc

 // 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.
 
 #include "media/base/bitstream_buffer.h"
 
 namespace media {
 
 BitstreamBuffer::BitstreamBuffer()
-    : id_(-1), size_(0), presentation_timestamp_(kNoTimestamp()) {}
-
-BitstreamBuffer::BitstreamBuffer(int32_t id,
-                                 base::SharedMemoryHandle handle,
-                                 size_t size)
-    : id_(id),
-      handle_(handle),
-      size_(size),
-      presentation_timestamp_(kNoTimestamp()) {}
+    : BitstreamBuffer(-1, base::SharedMemoryHandle(), 0) {}
 
 BitstreamBuffer::BitstreamBuffer(int32_t id,
                                  base::SharedMemoryHandle handle,
                                  size_t size,
+                                 off_t offset,
                                  base::TimeDelta presentation_timestamp)
     : id_(id),
       handle_(handle),
       size_(size),
+      offset_(offset),
       presentation_timestamp_(presentation_timestamp) {}
 
 BitstreamBuffer::BitstreamBuffer(const BitstreamBuffer& other) = default;
 
 BitstreamBuffer::~BitstreamBuffer() {}
 
 void BitstreamBuffer::SetDecryptConfig(const DecryptConfig& decrypt_config) {
   key_id_ = decrypt_config.key_id();
   iv_ = decrypt_config.iv();
   subsamples_ = decrypt_config.subsamples();
 }
 
 }  // namespace media