Fix unit test failures with estimated durations and splice frames.

media/filters/source_buffer_stream.cc

Index: media/filters/source_buffer_stream.cc
diff --git a/media/filters/source_buffer_stream.cc b/media/filters/source_buffer_stream.cc
index 0ff0f3f0efb023e166248743947caa18f2af2b10..909d8828a21892fe4bec5f80b015e75cb3475dea 100644
--- a/media/filters/source_buffer_stream.cc
+++ b/media/filters/source_buffer_stream.cc
@@ -490,7 +490,8 @@ bool SourceBufferStream::Append(const BufferQueue& buffers) {
     last_appended_buffer_timestamp_ = buffers.back()->GetDecodeTimestamp();
     last_appended_buffer_is_keyframe_ = buffers.back()->IsKeyframe();
   } else {
-    base::TimeDelta new_range_start_time = media_segment_start_time_;
+    base::TimeDelta new_range_start_time = std::min(
+        media_segment_start_time_, buffers.front()->GetDecodeTimestamp());
     const BufferQueue* buffers_for_new_range = &buffers;
     BufferQueue trimmed_buffers;
 
@@ -1672,8 +1673,12 @@ SourceBufferRange::SourceBufferRange(
 
 void SourceBufferRange::AppendBuffersToEnd(const BufferQueue& new_buffers) {
   DCHECK(buffers_.empty() || CanAppendBuffersToEnd(new_buffers));
+  DCHECK(media_segment_start_time_ == kNoTimestamp() ||
+         media_segment_start_time_ <=
+             new_buffers.front()->GetDecodeTimestamp());
   for (BufferQueue::const_iterator itr = new_buffers.begin();
-       itr != new_buffers.end(); ++itr) {
+       itr != new_buffers.end();
+       ++itr) {
     DCHECK((*itr)->GetDecodeTimestamp() != kNoTimestamp());
     buffers_.push_back(*itr);
     size_in_bytes_ += (*itr)->data_size();