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 6b9a66d13ae53f7b340853c49c9027649e611dd3..1bee6f9e810ec66416763aba4adc6dfb48961680 100644
--- a/media/base/stream_parser_buffer.cc
+++ b/media/base/stream_parser_buffer.cc
@@ -18,12 +18,6 @@ scoped_refptr<StreamParserBuffer> StreamParserBuffer::CopyFrom(
       new StreamParserBuffer(data, data_size, is_keyframe));
 }
 
-base::TimeDelta StreamParserBuffer::GetEndTimestamp() const {
-  DCHECK(GetTimestamp() != kNoTimestamp());
-  DCHECK(GetDuration() != kNoTimestamp());
-  return GetTimestamp() + GetDuration();
-}
-
 StreamParserBuffer::StreamParserBuffer(const uint8* data, int data_size,
                                        bool is_keyframe)
     : DecoderBuffer(data, data_size),
@@ -31,7 +25,6 @@ StreamParserBuffer::StreamParserBuffer(const uint8* data, int data_size,
   SetDuration(kNoTimestamp());
 }
 
-
 StreamParserBuffer::~StreamParserBuffer() {
 }