gpu: Add async pixel transfer interface, stub and tests.

ui/gl/async_pixel_transfer_delegate_stub.h

Index: ui/gl/async_pixel_transfer_delegate_stub.h
diff --git a/sync/api/sync_change_processor.cc b/ui/gl/async_pixel_transfer_delegate_stub.h
similarity index 61%
copy from sync/api/sync_change_processor.cc
copy to ui/gl/async_pixel_transfer_delegate_stub.h
index 4a0607e07f4349d9f06818e36b2a5b579b95a73b..109a6208b6161a48b1b21117e2da3a2ea2d9c5b7 100644
--- a/sync/api/sync_change_processor.cc
+++ b/ui/gl/async_pixel_transfer_delegate_stub.h
@@ -2,12 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "sync/api/sync_change_processor.h"
+#ifndef UI_GL_ASYNC_TASK_DELEGATE_STUB_H_
+#define UI_GL_ASYNC_TASK_DELEGATE_STUB_H_
 
-namespace syncer {
+namespace gfx {
+}  // namespace gfx
 
-SyncChangeProcessor::SyncChangeProcessor() {}
+#endif  // UI_GL_ASYNC_TASK_DELEGATE_ANDROID_H_
 
-SyncChangeProcessor::~SyncChangeProcessor() {}
-
-}  // namespace syncer