zero copy - NOT FOR REVIEW

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 16 matching lines @@
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/compositor/compositor_observer.h"
 #include "ui/compositor/compositor_switches.h"
 #include "ui/compositor/compositor_vsync_manager.h"
 #include "ui/compositor/dip_util.h"
 #include "ui/compositor/layer.h"
 #include "ui/gfx/frame_time.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_switches.h"
 
+extern char GetZCopy();
+
 namespace {
 
 const double kDefaultRefreshRate = 60.0;
 const double kTestRefreshRate = 200.0;
 
 enum SwapType {
   DRAW_SWAP,
 };
 
 bool g_compositor_initialized = false;
@@ skipping 187 matching lines @@
   settings.initial_debug_state.show_replica_screen_space_rects =
       command_line->HasSwitch(cc::switches::kUIShowReplicaScreenSpaceRects);
   settings.initial_debug_state.show_occluding_rects =
       command_line->HasSwitch(cc::switches::kUIShowOccludingRects);
   settings.initial_debug_state.show_non_occluding_rects =
       command_line->HasSwitch(cc::switches::kUIShowNonOccludingRects);
 
   settings.initial_debug_state.SetRecordRenderingStats(
       command_line->HasSwitch(cc::switches::kEnableGpuBenchmarking));
 
+  if (GetZCopy()) {
+    settings.impl_side_painting = true;
+    settings.use_map_image = true;
+  }
+
   base::TimeTicks before_create = base::TimeTicks::Now();
   if (!!g_compositor_thread) {
     host_ = cc::LayerTreeHost::CreateThreaded(
         this, NULL, settings, g_compositor_thread->message_loop_proxy());
   } else {
     host_ = cc::LayerTreeHost::CreateSingleThreaded(this, this, NULL, settings);
   }
   UMA_HISTOGRAM_TIMES("GPU.CreateBrowserCompositor",
                       base::TimeTicks::Now() - before_create);
   host_->SetRootLayer(root_web_layer_);
@@ skipping 301 matching lines @@
     // CompositorObservers to be notified before starting another
     // draw cycle.
     ScheduleDraw();
   }
   FOR_EACH_OBSERVER(CompositorObserver,
                     observer_list_,
                     OnCompositingEnded(this));
 }
 
 }  // namespace ui