Remove buffer duration calculation from WebMClusterParser and update SourceBufferStream accordingly

media/base/stream_parser_buffer.cc

Index: media/base/stream_parser_buffer.cc
diff --git a/media/base/stream_parser_buffer.cc b/media/base/stream_parser_buffer.cc
index 4dc7252e2b87b6c10381e85c835e725868d01b5b..85013723057cf1dd4962658c3a39a9430f3ef811 100644
--- a/media/base/stream_parser_buffer.cc
+++ b/media/base/stream_parser_buffer.cc
@@ -28,12 +28,6 @@ void StreamParserBuffer::SetDecodeTimestamp(const base::TimeDelta& timestamp) {
   decode_timestamp_ = timestamp;
 }
 
-base::TimeDelta StreamParserBuffer::GetEndTimestamp() const {
-  DCHECK(GetDecodeTimestamp() != kNoTimestamp());
-  DCHECK(GetDuration() != kNoTimestamp());
-  return GetDecodeTimestamp() + GetDuration();
-}
-
 StreamParserBuffer::StreamParserBuffer(const uint8* data, int data_size,
                                        bool is_keyframe)
     : DecoderBuffer(data, data_size),
@@ -42,7 +36,6 @@ StreamParserBuffer::StreamParserBuffer(const uint8* data, int data_size,
   SetDuration(kNoTimestamp());
 }
 
-
 StreamParserBuffer::~StreamParserBuffer() {
 }