Add Blink-side flag for enabling/disabling layer squashing.

Source/core/page/Settings.h

 /*
  * Copyright (C) 2003, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 147 matching lines @@
         // FIXME: Remove and uncomment once chromium side changes land.
         return true;
         // return m_viewportMetaEnabled;
     }
 
     // FIXME: This is a temporary flag and should be removed once accelerated
     // overflow scroll is ready (crbug.com/254111).
     void setCompositorDrivenAcceleratedScrollingEnabled(bool enabled) { m_compositorDrivenAcceleratedScrollingEnabled = enabled; }
     bool isCompositorDrivenAcceleratedScrollingEnabled() const { return m_compositorDrivenAcceleratedScrollingEnabled; }
 
+    // FIXME: This is a temporary flag and should be removed when squashing is ready.
+    // (crbug.com/261605)
+    void setLayerSquashingEnabled(bool enabled) { m_layerSquashingEnabled = enabled; }
+    bool isLayerSquashingEnabled() const { return m_layerSquashingEnabled; }
+
 private:
     explicit Settings(Page*);
 
     Page* m_page;
 
     String m_mediaTypeOverride;
     ScriptFontFamilyMap m_standardFontFamilyMap;
     ScriptFontFamilyMap m_serifFontFamilyMap;
     ScriptFontFamilyMap m_fixedFontFamilyMap;
     ScriptFontFamilyMap m_sansSerifFontFamilyMap;
@@ skipping 18 matching lines @@
 
     bool m_touchEventEmulationEnabled : 1;
     bool m_openGLMultisamplingEnabled : 1;
     bool m_viewportEnabled : 1;
     bool m_viewportMetaEnabled : 1;
 
     // FIXME: This is a temporary flag and should be removed once accelerated
     // overflow scroll is ready (crbug.com/254111).
     bool m_compositorDrivenAcceleratedScrollingEnabled : 1;
 
+    // FIXME: This is a temporary flag and should be removed when squashing is ready.
+    bool m_layerSquashingEnabled : 1;
+
     Timer<Settings> m_setImageLoadingSettingsTimer;
     void imageLoadingSettingsTimerFired(Timer<Settings>*);
     void recalculateTextAutosizingMultipliers();
 };
 
 } // namespace WebCore
 
 #endif // Settings_h