Revert of Revert of Merge VideoDecodeAcceleratorImpl with VideoDecodeAccelerator (https://codereview.chromium.org/319323002/)

Reason for revert:
Relanding since the failure appears to be unrelated.

Original issue's description:
> Revert of Merge VideoDecodeAcceleratorImpl with VideoDecodeAccelerator (https://codereview.chromium.org/317083003/)
> 
> Reason for revert:
> Speculative revert to fix content_unittest failures in http://build.chromium.org/p/chromium.linux/builders/Android%20Tests%20%28dbg%29/builds/20807
> 
> Original issue's description:
> > Merge VideoDecodeAcceleratorImpl with VideoDecodeAccelerator
> > 
> > This moves the single method CanDecodeOnIOThread on
> > VideoDecodeAcceleratorImpl to VideoDecodeAccelerator. The
> > implementations that were subclasses of VideoDecodeAcceleratorImpl now
> > get an override for CanDecodeOnIOThread that returns false.
> > 
> > TEST=linux desktop build
> > BUG=380884
> > 
> > Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=275621
> 
> TBR=scherkus@chromium.org,fischman@chromium.org,spang@chromium.org
> NOTREECHECKS=true
> NOTRY=true
> BUG=380884
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=275636

TBR=scherkus@chromium.org,fischman@chromium.org,spang@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=380884

Review URL: https://codereview.chromium.org/318243002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@275669 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 20 insertions, 0 deletions

diff --git a/media/video/mock_video_decode_accelerator.h b/media/video/mock_video_decode_accelerator.h
index 4568ab6..f8bb6da 100644
--- a/media/video/mock_video_decode_accelerator.h
+++ b/media/video/mock_video_decode_accelerator.h
@@ -32,6 +32,7 @@ class MockVideoDecodeAccelerator : public VideoDecodeAccelerator {
   MOCK_METHOD0(Flush, void());
   MOCK_METHOD0(Reset, void());
   MOCK_METHOD0(Destroy, void());
+  MOCK_METHOD0(CanDecodeOnIOThread, bool());
 
  private:
   void DeleteThis();
diff --git a/media/video/video_decode_accelerator.cc b/media/video/video_decode_accelerator.cc
index 142dab3..a72912c 100644
--- a/media/video/video_decode_accelerator.cc
+++ b/media/video/video_decode_accelerator.cc
@@ -4,12 +4,20 @@
 
 #include "media/video/video_decode_accelerator.h"
 
+#include "base/logging.h"
+
 namespace media {
 
 VideoDecodeAccelerator::~VideoDecodeAccelerator() {}
 
+bool VideoDecodeAccelerator::CanDecodeOnIOThread() {
+  // GPU process subclasses must override this.
+  LOG(FATAL) << "This should only get called in the GPU process";
+  return false;  // not reached
 }
 
+} // namespace media
+
 namespace base {
 
 void DefaultDeleter<media::VideoDecodeAccelerator>::operator()(
diff --git a/media/video/video_decode_accelerator.h b/media/video/video_decode_accelerator.h
index 7025a51..4df3b1c 100644
--- a/media/video/video_decode_accelerator.h
+++ b/media/video/video_decode_accelerator.h
@@ -132,6 +132,17 @@ class MEDIA_EXPORT VideoDecodeAccelerator {
   // unconditionally, so make sure to drop all pointers to it!
   virtual void Destroy() = 0;
 
+  // GPU PROCESS ONLY.  Implementations of this interface in the
+  // content/common/gpu/media should implement this, and implementations in
+  // other processes should not override the default implementation.
+  // Returns true if VDA::Decode and VDA::Client callbacks can run on the IO
+  // thread. Otherwise they will run on the GPU child thread. The purpose of
+  // running Decode on the IO thread is to reduce decode latency. Note Decode
+  // should return as soon as possible and not block on the IO thread. Also,
+  // PictureReady should be run on the child thread if a picture is delivered
+  // the first time so it can be cleared.
+  virtual bool CanDecodeOnIOThread();
+
  protected:
   // Do not delete directly; use Destroy() or own it with a scoped_ptr, which
   // will Destroy() it properly by default.