Aura: Support --enable-partial-swap with --composite-to-mailbox

content/renderer/gpu/mailbox_output_surface.cc

 // Copyright (c) 2012 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.
 
 #include "content/renderer/gpu/mailbox_output_surface.h"
 
 #include "base/logging.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_ack.h"
 #include "cc/output/gl_frame_data.h"
@@ skipping 145 matching lines @@
     uint32 texture_id = pending_textures_.front().texture_id;
     if (texture_id)
       context3d_->deleteTexture(texture_id);
     pending_textures_.pop_front();
   }
   CompositorOutputSurface::OnSwapAck(ack);
 }
 
 void MailboxOutputSurface::SwapBuffers(cc::CompositorFrame* frame) {
   DCHECK(frame->gl_frame_data);
-  DCHECK(frame->gl_frame_data->sub_buffer_rect.size() ==
-         frame->gl_frame_data->size)
-      << "Partial swap not supported with composite-to-mailbox yet.";
-
   DCHECK(!surface_size_.IsEmpty());
   DCHECK(surface_size_ == current_backing_.size);
   DCHECK(frame->gl_frame_data->size == current_backing_.size);
   DCHECK(!current_backing_.mailbox.IsZero());
 
   frame->gl_frame_data->mailbox = current_backing_.mailbox;
   context3d_->flush();
   frame->gl_frame_data->sync_point = context3d_->insertSyncPoint();
   CompositorOutputSurface::SwapBuffers(frame);
 
   pending_textures_.push_back(current_backing_);
   current_backing_ = TransferableFrame();
 }
 
 size_t MailboxOutputSurface::GetNumAcksPending() {
   DCHECK(pending_textures_.size());
   return pending_textures_.size() - 1;
 }
 
 }  // namespace content