aura: Enable use_canvas_skia=1 on aura.

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 "base/threading/thread_restrictions.h"
 #include "third_party/skia/include/images/SkImageEncoder.h"
 #include "third_party/skia/include/core/SkBitmap.h"
@@ skipping 105 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
 
 #if defined(WEBLAYERTREEVIEW_HAS_INITIALIZE)
   host_.initialize(this, root_web_layer_, settings);
 #else
   host_ = WebKit::WebLayerTreeView::create(this, root_web_layer_, settings);
 #endif
   root_web_layer_.setAnchorPoint(WebKit::WebFloatPoint(0.f, 0.f));
   WidgetSizeChanged(size_);
 }
 
@@ skipping 194 matching lines @@
 
 COMPOSITOR_EXPORT void DisableTestCompositor() {
   test_compositor_enabled = false;
 }
 
 COMPOSITOR_EXPORT bool IsTestCompositorEnabled() {
   return test_compositor_enabled;
 }
 
 }  // namespace ui