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

content/common/gpu/media/vaapi_video_decode_accelerator.h

Index: content/common/gpu/media/vaapi_video_decode_accelerator.h
diff --git a/content/common/gpu/media/vaapi_video_decode_accelerator.h b/content/common/gpu/media/vaapi_video_decode_accelerator.h
index 9ac73da353e7952ec588b4d20f0b5d46c702d54e..1755b98f3d5e37749b36bd36ee5f2b84644c118d 100644
--- a/content/common/gpu/media/vaapi_video_decode_accelerator.h
+++ b/content/common/gpu/media/vaapi_video_decode_accelerator.h
@@ -25,6 +25,7 @@
 #include "content/common/content_export.h"
 #include "content/common/gpu/media/vaapi_h264_decoder.h"
 #include "content/common/gpu/media/vaapi_wrapper.h"
+#include "content/common/gpu/media/video_decode_accelerator_impl.h"
 #include "media/base/bitstream_buffer.h"
 #include "media/video/picture.h"
 #include "media/video/video_decode_accelerator.h"
@@ -40,8 +41,8 @@ namespace content {
 // ChildThread.  A few methods on it are called on the decoder thread which is
 // stopped during |this->Destroy()|, so any tasks posted to the decoder thread
 // can assume |*this| is still alive.  See |weak_this_| below for more details.
-class CONTENT_EXPORT VaapiVideoDecodeAccelerator :
-    public media::VideoDecodeAccelerator {
+class CONTENT_EXPORT VaapiVideoDecodeAccelerator
+    : public VideoDecodeAcceleratorImpl {
  public:
   VaapiVideoDecodeAccelerator(
       Display* x_display, GLXContext glx_context,