Add per-tile painting support to compositor.

ui/gfx/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/gfx/compositor/compositor.h"
 
 #include "base/command_line.h"
 #include "third_party/skia/include/images/SkImageEncoder.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebCompositor.h"
@@ skipping 118 matching lines @@
   WebKit::WebLayerTreeView::Settings settings;
   CommandLine* command_line = CommandLine::ForCurrentProcess();
   settings.showFPSCounter =
       command_line->HasSwitch(switches::kUIShowFPSCounter);
   settings.showPlatformLayerTree =
       command_line->HasSwitch(switches::kUIShowLayerTree);
   settings.refreshRate = test_compositor_enabled ?
       kTestRefreshRate : kDefaultRefreshRate;
   settings.partialSwapEnabled =
       command_line->HasSwitch(switches::kUIEnablePartialSwap);
+#if defined(PER_TILE_PAINTING)
+  settings.perTilePainting =
+    command_line->HasSwitch(switches::kUIEnablePerTilePainting);
+#endif
 
   host_ = WebKit::WebLayerTreeView::create(this, root_web_layer_, settings);
   root_web_layer_.setAnchorPoint(WebKit::WebFloatPoint(0.f, 0.f));
   WidgetSizeChanged(size_);
 }
 
 Compositor::~Compositor() {
   // There's a cycle between |root_web_layer_| and |host_|, which results in
   // leaking and/or crashing. Explicitly set the root layer to NULL so the cycle
   // is broken.
@@ skipping 171 matching lines @@
       switches::kDisableTestCompositor)) {
     test_compositor_enabled = true;
   }
 }
 
 COMPOSITOR_EXPORT void DisableTestCompositor() {
   test_compositor_enabled = false;
 }
 
 }  // namespace ui