Introduce GpuVideoDecodeAcceleratorFactory.

content/common/gpu/media/vt_video_decode_accelerator_mac.h

Index: content/common/gpu/media/vt_video_decode_accelerator_mac.h
diff --git a/content/common/gpu/media/vt_video_decode_accelerator_mac.h b/content/common/gpu/media/vt_video_decode_accelerator_mac.h
index 2d222163823e4e7cf603d444761741c4c131c059..a1a93644cc180081699f2bd6033f5a2a576c785a 100644
--- a/content/common/gpu/media/vt_video_decode_accelerator_mac.h
+++ b/content/common/gpu/media/vt_video_decode_accelerator_mac.h
@@ -18,6 +18,7 @@
 #include "base/threading/thread.h"
 #include "base/threading/thread_checker.h"
 #include "content/common/gpu/media/vt_mac.h"
+#include "content/public/common/gpu_video_decode_accelerator_helpers.h"
 #include "media/filters/h264_parser.h"
 #include "media/video/h264_poc.h"
 #include "media/video/video_decode_accelerator.h"
@@ -35,9 +36,9 @@ bool InitializeVideoToolbox();
 class VTVideoDecodeAccelerator : public media::VideoDecodeAccelerator {
  public:
   explicit VTVideoDecodeAccelerator(
-      const base::Callback<bool(void)>& make_context_current,
-      const base::Callback<
-          void(uint32_t, uint32_t, scoped_refptr<gl::GLImage>)>& bind_image);
+      const gpu_vda_helpers::MakeGLContextCurrentCb& make_context_current_cb,
+      const gpu_vda_helpers::BindGLImageCb& bind_image_cb);
+
   ~VTVideoDecodeAccelerator() override;
 
   // VideoDecodeAccelerator implementation.
@@ -49,7 +50,10 @@ class VTVideoDecodeAccelerator : public media::VideoDecodeAccelerator {
   void Flush() override;
   void Reset() override;
   void Destroy() override;
-  bool CanDecodeOnIOThread() override;
+  bool TryInitializeDecodeOnSeparateThread(
+      const base::WeakPtr<Client>& decode_client,
+      const scoped_refptr<base::SingleThreadTaskRunner>& decode_task_runner)
+      override;
 
   // Called by OutputThunk() when VideoToolbox finishes decoding a frame.
   void Output(
@@ -189,9 +193,8 @@ class VTVideoDecodeAccelerator : public media::VideoDecodeAccelerator {
   //
   // GPU thread state.
   //
-  base::Callback<bool(void)> make_context_current_;
-  base::Callback<void(uint32_t, uint32_t, scoped_refptr<gl::GLImage>)>
-      bind_image_;
+  gpu_vda_helpers::MakeGLContextCurrentCb make_context_current_cb_;
+  gpu_vda_helpers::BindGLImageCb bind_image_cb_;
   media::VideoDecodeAccelerator::Client* client_;
   State state_;