Run VDA::Decode on GPU IO thread if VDA supports it.

content/common/gpu/media/exynos_video_decode_accelerator.cc

Index: content/common/gpu/media/exynos_video_decode_accelerator.cc
diff --git a/content/common/gpu/media/exynos_video_decode_accelerator.cc b/content/common/gpu/media/exynos_video_decode_accelerator.cc
index 677df9c350470545a468614d8b3e08f8b7fe94bd..6918061b3715f7f3ba6235d80171a2a182b69bfd 100644
--- a/content/common/gpu/media/exynos_video_decode_accelerator.cc
+++ b/content/common/gpu/media/exynos_video_decode_accelerator.cc
@@ -205,8 +205,10 @@ ExynosVideoDecodeAccelerator::ExynosVideoDecodeAccelerator(
     EGLDisplay egl_display,
     EGLContext egl_context,
     Client* client,
-    const base::Callback<bool(void)>& make_context_current)
+    const base::Callback<bool(void)>& make_context_current,
+    const scoped_refptr<base::MessageLoopProxy>& io_message_loop_proxy)
     : child_message_loop_proxy_(base::MessageLoopProxy::current()),
+      io_message_loop_proxy_(io_message_loop_proxy),
       weak_this_(base::AsWeakPtr(this)),
       client_ptr_factory_(client),
       client_(client_ptr_factory_.GetWeakPtr()),
@@ -415,23 +417,12 @@ void ExynosVideoDecodeAccelerator::Decode(
     const media::BitstreamBuffer& bitstream_buffer) {
   DVLOG(1) << "Decode(): input_id=" << bitstream_buffer.id()
            << ", size=" << bitstream_buffer.size();
-  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
-
-  scoped_ptr<BitstreamBufferRef> bitstream_record(new BitstreamBufferRef(
-      client_, child_message_loop_proxy_,
-      new base::SharedMemory(bitstream_buffer.handle(), true),
-      bitstream_buffer.size(), bitstream_buffer.id()));
-  if (!bitstream_record->shm->Map(bitstream_buffer.size())) {
-    DLOG(ERROR) << "Decode(): could not map bitstream_buffer";
-    NOTIFY_ERROR(UNREADABLE_INPUT);
-    return;
-  }
-  DVLOG(3) << "Decode(): mapped to addr=" << bitstream_record->shm->memory();
+  DCHECK(io_message_loop_proxy_->BelongsToCurrentThread());
 
   // DecodeTask() will take care of running a DecodeBufferTask().
   decoder_thread_.message_loop()->PostTask(FROM_HERE, base::Bind(
       &ExynosVideoDecodeAccelerator::DecodeTask, base::Unretained(this),
-      base::Passed(&bitstream_record)));
+      bitstream_buffer));
 }
 
 void ExynosVideoDecodeAccelerator::AssignPictureBuffers(
@@ -610,12 +601,23 @@ bool ExynosVideoDecodeAccelerator::PostSandboxInitialization() {
 }
 
 void ExynosVideoDecodeAccelerator::DecodeTask(
-    scoped_ptr<BitstreamBufferRef> bitstream_record) {
-  DVLOG(3) << "DecodeTask(): input_id=" << bitstream_record->input_id;
+    const media::BitstreamBuffer& bitstream_buffer) {

[Ami GONE FROM CHROMIUM, 2013/08/27 17:10:33]

This is problematic: bitstream_buffer may go out of scope and/or be reused after
Decode() ends, so the const& may be invalid here.
Simplest just to pass by copy so the Bind in Decode will copy the handle there.

[Pawel Osciak, 2013/08/28 08:36:49]

Probably. Or create BBR in Decode and only Map() here. But copy is simpler.

[wuchengli, 2013/08/28 13:18:21]

This should be OK. callback.h says "By default Bind() will store
copies of all bound parameters, and attempt to refcount a target
object if the function being bound is a class method. These copies
are created even if the function takes parameters as const
references."

[wuchengli, 2013/08/28 13:18:21]

I agree with Antoine that we should make IO thread as responsive as possible. So
I'll keep BitstreamBufferRef creation here.

+  DVLOG(3) << "DecodeTask(): input_id=" << bitstream_buffer.id();
   DCHECK_EQ(decoder_thread_.message_loop(), base::MessageLoop::current());
   DCHECK_NE(decoder_state_, kUninitialized);
   TRACE_EVENT1("Video Decoder", "EVDA::DecodeTask", "input_id",
-               bitstream_record->input_id);
+               bitstream_buffer.id());
+
+  scoped_ptr<BitstreamBufferRef> bitstream_record(new BitstreamBufferRef(
+      client_, child_message_loop_proxy_,
+      new base::SharedMemory(bitstream_buffer.handle(), true),
+      bitstream_buffer.size(), bitstream_buffer.id()));
+  if (!bitstream_record->shm->Map(bitstream_buffer.size())) {
+    DLOG(ERROR) << "Decode(): could not map bitstream_buffer";
+    NOTIFY_ERROR(UNREADABLE_INPUT);
+    return;
+  }
+  DVLOG(3) << "Decode(): mapped to addr=" << bitstream_record->shm->memory();
 
   if (decoder_state_ == kResetting || decoder_flushing_) {
     // In the case that we're resetting or flushing, we need to delay decoding