Support start trimming post-decoding. Use it with FFmpegDemuxer.

media/base/decoder_buffer.h

 // 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.
 
 #ifndef MEDIA_BASE_DECODER_BUFFER_H_
 #define MEDIA_BASE_DECODER_BUFFER_H_
 
 #include <string>
+#include <utility>
 
 #include "base/logging.h"
 #include "base/memory/aligned_memory.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "media/base/decrypt_config.h"
 #include "media/base/media_export.h"
 
@@ skipping 79 matching lines @@
   const uint8* side_data() const {
     DCHECK(!end_of_stream());
     return side_data_.get();
   }
 
   int side_data_size() const {
     DCHECK(!end_of_stream());
     return side_data_size_;
   }
 
-  base::TimeDelta discard_padding() const {
+  // A discard window indicates the amount of data which should be discard from
+  // this buffer after decoding.  The first value is the amount of the front and
+  // the second the amount off the back.
+  typedef std::pair<base::TimeDelta, base::TimeDelta> DiscardPadding;
+  const DiscardPadding& discard_padding() const {
     DCHECK(!end_of_stream());
     return discard_padding_;
   }
 
-  void set_discard_padding(const base::TimeDelta discard_padding) {
+  void set_discard_padding(const DiscardPadding& discard_padding) {
     DCHECK(!end_of_stream());
     discard_padding_ = discard_padding;
   }
 
   const DecryptConfig* decrypt_config() const {
     DCHECK(!end_of_stream());
     return decrypt_config_.get();
   }
 
   void set_decrypt_config(scoped_ptr<DecryptConfig> decrypt_config) {
@@ skipping 35 matching lines @@
 
  private:
   base::TimeDelta timestamp_;
   base::TimeDelta duration_;
 
   int size_;
   scoped_ptr<uint8, base::AlignedFreeDeleter> data_;
   int side_data_size_;
   scoped_ptr<uint8, base::AlignedFreeDeleter> side_data_;
   scoped_ptr<DecryptConfig> decrypt_config_;
-  base::TimeDelta discard_padding_;
+  DiscardPadding discard_padding_;
   base::TimeDelta splice_timestamp_;
 
   // Constructor helper method for memory allocations.
   void Initialize();
 
   DISALLOW_COPY_AND_ASSIGN(DecoderBuffer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_DECODER_BUFFER_H_