cc: Partial tile update for one-copy raster.

ui/compositor/compositor.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 "ui/compositor/compositor.h"
 
 #include <algorithm>
 #include <deque>
 
 #include "base/bind.h"
@@ skipping 124 matching lines @@
   settings.use_one_copy = IsUIOneCopyEnabled();
 
   // TODO(reveman): We currently assume that the compositor will use BGRA_8888
   // if it's able to, and RGBA_8888 otherwise. Since we don't know what it will
   // use we hardcode BGRA_8888 here for now. We should instead
   // move decisions about GpuMemoryBuffer format to the browser embedder so we
   // know it here, and pass that decision to the compositor for each usage.
   // crbug.com/490362
   gfx::GpuMemoryBuffer::Format format = gfx::GpuMemoryBuffer::BGRA_8888;
 
-  gfx::GpuMemoryBuffer::Usage usage = gfx::GpuMemoryBuffer::MAP;
-  // TODO(danakj): Do this for partial raster:
   // Use PERSISTENT_MAP memory buffers to support partial tile raster for
   // software raster into GpuMemoryBuffers.
-  // gfx::GpuMemoryBuffer::Usage usage = gfx::GpuMemoryBuffer::PERSISTENT_MAP;
-  // settings.use_persistent_map_gpu_memory_buffer_usage = true;
+  gfx::GpuMemoryBuffer::Usage usage = gfx::GpuMemoryBuffer::PERSISTENT_MAP;
+  settings.use_persistent_map_for_gpu_memory_buffers = true;
 
   settings.use_image_texture_target =
       context_factory_->GetImageTextureTarget(format, usage);
 
   // Note: gathering of pixel refs is only needed when using multiple
   // raster threads.
   settings.gather_pixel_refs = false;
 
   base::TimeTicks before_create = base::TimeTicks::Now();
 
@@ skipping 296 matching lines @@
                     observer_list_,
                     OnCompositingLockStateChanged(this));
 }
 
 void Compositor::CancelCompositorLock() {
   if (compositor_lock_)
     compositor_lock_->CancelLock();
 }
 
 }  // namespace ui