gpu: Implement idle async pixel transfers.

ui/gl/async_pixel_transfer_delegate.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GL_ASYNC_TASK_DELEGATE_H_
 #define UI_GL_ASYNC_TASK_DELEGATE_H_
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 95 matching lines @@
       const AsyncTexSubImage2DParams& tex_params,
       const AsyncMemoryParams& mem_params) = 0;
 
   // Block until the specified transfer completes.
   virtual void WaitForTransferCompletion(
       AsyncPixelTransferState* state) = 0;
 
   virtual uint32 GetTextureUploadCount() = 0;
   virtual base::TimeDelta GetTotalTextureUploadTime() = 0;
 
+  virtual void ProcessPendingTransfers() = 0;

[Sami, 2013/03/07 16:57:19]

Can we name these somehow so that the distinction between off- and on-thread
transfers is clear? I think having the Android delegate always return false from
a function called HasPendingTransfers seems weird.

ProcessPendingIdleTransfers maybe? At least let's put a comment here.

[reveman, 2013/03/07 20:21:04]

I agree.
I renamed HasPendingTransfers() to CanProcessPendingTransfers() and added a
comment that explains what these functions are for.

+  virtual bool HasPendingTransfers() = 0;
+
  protected:
   AsyncPixelTransferDelegate() {}
   // For testing, as returning scoped_ptr wouldn't work with MOCK_METHOD.
   virtual AsyncPixelTransferState*
       CreateRawPixelTransferState(GLuint texture_id) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AsyncPixelTransferDelegate);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_ASYNC_TASK_DELEGATE_H_