Don't reset the codec state for a flush; this kills the frames.

media/gpu/android_video_decode_accelerator.cc

Index: media/gpu/android_video_decode_accelerator.cc
diff --git a/media/gpu/android_video_decode_accelerator.cc b/media/gpu/android_video_decode_accelerator.cc
index 50fe2ebca4ece288bff98a1135b8baa2d94a0966..6d549f08e5e8764be69169fb5a3967fdd11aad42 100644
--- a/media/gpu/android_video_decode_accelerator.cc
+++ b/media/gpu/android_video_decode_accelerator.cc
@@ -383,6 +383,7 @@ AndroidVideoDecodeAccelerator::AndroidVideoDecodeAccelerator(
       error_sequence_token_(0),
       defer_errors_(false),
       deferred_initialization_pending_(false),
+      codec_needs_reset_(false),
       weak_this_factory_(this) {}
 
 AndroidVideoDecodeAccelerator::~AndroidVideoDecodeAccelerator() {
@@ -900,6 +901,11 @@ void AndroidVideoDecodeAccelerator::Decode(
     const media::BitstreamBuffer& bitstream_buffer) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
+  // If we previously deferred a codec restart, take care of it now. This can

[Tima Vaisburd, 2016/05/24 19:06:26]

Do you want to DCHECK that drain_type_ == DRAIN_TYPE_NONE ?

[DaleCurtis, 2016/05/24 23:53:14]

Done.

+  // happen on older devices where configuration changes require a codec reset.
+  if (codec_needs_reset_)
+    ResetCodecState(base::Closure());
+
   if (bitstream_buffer.id() >= 0 && bitstream_buffer.size() > 0) {
     DecodeBuffer(bitstream_buffer);
     return;
@@ -1179,6 +1185,17 @@ void AndroidVideoDecodeAccelerator::ResetCodecState(
   const bool did_codec_error_happen = state_ == ERROR;
   state_ = NO_ERROR;
 
+  // Don't reset the codec here if there's no error and we're only flushing;
+  // instead defer until the next decode call; this prevents us from unbacking
+  // frames that might be out for display at end of stream.
+  codec_needs_reset_ = false;
+  if (drain_type_ == DRAIN_FOR_FLUSH && !did_codec_error_happen) {

[watk, 2016/05/24 19:47:26]

Can we do this even if there's no drain going on? Then this would also fix the
unnecessary codec creation we do for Suspends for fullscreen 
https://bugs.chromium.org/p/chromium/issues/detail?id=599288

[DaleCurtis, 2016/05/24 23:53:14]

We probably can, but doing so exposed a few issues with how we're handling reset
right now. Namely that ERROR state is non-terminal and ResetCodecState can
escape out of it. Probably this should be fixed first, so I'm going to defer
this change to a followup CL.

+    codec_needs_reset_ = true;
+    if (!done_cb.is_null())
+      done_cb.Run();
+    return;
+  }
+
   // We might increment error_sequence_token here to cancel any delayed errors,
   // but right now it's unclear that it's safe to do so.  If we are in an error
   // state because of a codec error, then it would be okay.  Otherwise, it's