Reland: MSE: Relax the 'media segment must begin with keyframe' requirement

media/filters/source_buffer_range.cc

Index: media/filters/source_buffer_range.cc
diff --git a/media/filters/source_buffer_range.cc b/media/filters/source_buffer_range.cc
index 562e14e0964a4ebdaf438598a6de4670732b2b79..a2b6e8221d2d2129758d9f42ef0626b5812e4da1 100644
--- a/media/filters/source_buffer_range.cc
+++ b/media/filters/source_buffer_range.cc
@@ -22,9 +22,10 @@ static bool CompareStreamParserBufferToTimeDelta(
   return buffer->GetDecodeTimestamp() < decode_timestamp;
 }
 
-bool SourceBufferRange::AllowSameTimestamp(
-    bool prev_is_keyframe, bool current_is_keyframe) {
-  return prev_is_keyframe || !current_is_keyframe;
+bool SourceBufferRange::IsUncommonSameTimestampSequence(
+    bool prev_is_keyframe,
+    bool current_is_keyframe) {
+  return current_is_keyframe && !prev_is_keyframe;

[chcunningham, 2016/02/09 00:21:08]

Just to note: I wasn't sure how (un)common this is in the case of VP9 alt-ref
frames. Word from fgalligan@ is that an alt-ref frame is *almost always*
followed by a non-key frame. In other words, "uncommon" (rather than
"impossible" or "error") is a good choice of naming here...  

[wolenetz, 2016/02/09 00:47:19]

Acknowledged.

 }
 
 SourceBufferRange::SourceBufferRange(
@@ -487,14 +488,13 @@ bool SourceBufferRange::CanAppendRangeToEnd(
 bool SourceBufferRange::CanAppendBuffersToEnd(
     const BufferQueue& buffers) const {
   DCHECK(!buffers_.empty());
-  return IsNextInSequence(buffers.front()->GetDecodeTimestamp(),
-                          buffers.front()->is_key_frame());
+  return IsNextInSequence(buffers.front()->GetDecodeTimestamp());
 }
 
 bool SourceBufferRange::BelongsToRange(DecodeTimestamp timestamp) const {
   DCHECK(!buffers_.empty());
 
-  return (IsNextInSequence(timestamp, false) ||
+  return (IsNextInSequence(timestamp) ||
           (GetStartTimestamp() <= timestamp && timestamp <= GetEndTimestamp()));
 }
 
@@ -570,17 +570,11 @@ DecodeTimestamp SourceBufferRange::KeyframeBeforeTimestamp(
   return GetFirstKeyframeAtOrBefore(timestamp)->first;
 }
 
-bool SourceBufferRange::IsNextInSequence(
-    DecodeTimestamp timestamp, bool is_key_frame) const {
+bool SourceBufferRange::IsNextInSequence(DecodeTimestamp timestamp) const {
   DecodeTimestamp end = buffers_.back()->GetDecodeTimestamp();
-  if (end < timestamp &&
-      (gap_policy_ == ALLOW_GAPS ||
-       timestamp <= end + GetFudgeRoom())) {
-    return true;
-  }
-
-  return timestamp == end && AllowSameTimestamp(
-      buffers_.back()->is_key_frame(), is_key_frame);
+  return (end == timestamp ||
+          (end < timestamp &&
+           (gap_policy_ == ALLOW_GAPS || timestamp <= end + GetFudgeRoom())));
 }
 
 base::TimeDelta SourceBufferRange::GetFudgeRoom() const {