cc: one copy is default as well as final fallback.

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 107 matching lines @@
       command_line->HasSwitch(cc::switches::kUIShowScreenSpaceRects);
   settings.initial_debug_state.show_replica_screen_space_rects =
       command_line->HasSwitch(cc::switches::kUIShowReplicaScreenSpaceRects);
 
   settings.initial_debug_state.SetRecordRenderingStats(
       command_line->HasSwitch(cc::switches::kEnableGpuBenchmarking));
 
   settings.use_display_lists = true;
 
   settings.use_zero_copy = IsUIZeroCopyEnabled();
-  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;
 
   // Use PERSISTENT_MAP memory buffers to support partial tile raster for
@@ skipping 309 matching lines @@
                     observer_list_,
                     OnCompositingLockStateChanged(this));
 }
 
 void Compositor::CancelCompositorLock() {
   if (compositor_lock_)
     compositor_lock_->CancelLock();
 }
 
 }  // namespace ui