Make deferred image decoding default to on.

Source/web/WebSettingsImpl.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 194 matching lines @@
     void setMockGestureTapHighlightsEnabled(bool);
     bool mockGestureTapHighlightsEnabled() const;
 
 private:
     Settings* m_settings;
     DevToolsEmulator* m_devToolsEmulator;
     bool m_showFPSCounter;
     bool m_showPaintRects;
     bool m_renderVSyncNotificationEnabled;
     bool m_autoZoomFocusedNodeToLegibleScale;
-    bool m_deferredImageDecodingEnabled;
     bool m_perTilePaintingEnabled;
     bool m_supportDeprecatedTargetDensityDPI;
     bool m_shrinksViewportContentToFit;
     // This quirk is to maintain compatibility with Android apps built on
     // the Android SDK prior to and including version 18. Presumably, this
     // can be removed any time after 2015. See http://crbug.com/277369.
     bool m_viewportMetaLayoutSizeQuirk;
     // This quirk is to maintain compatibility with Android apps built on
     // the Android SDK prior to and including version 18. Presumably, this
     // can be removed any time after 2015. See http://crbug.com/312691.
     bool m_viewportMetaNonUserScalableQuirk;
     // This quirk is to maintain compatibility with Android apps built on
     // the Android SDK prior to and including version 18. Presumably, this
     // can be removed any time after 2015. See http://crbug.com/313754.
     bool m_clobberUserAgentInitialScaleQuirk;
     bool m_mainFrameResizesAreOrientationChanges;
 };
 
 } // namespace blink
 
 #endif