Add support for Low Priorirty tasks.

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 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 96 matching lines @@
 #include "platform/UserGestureIndicator.h"
 #include "platform/exported/WebActiveGestureAnimation.h"
 #include "platform/fonts/FontCache.h"
 #include "platform/graphics/Color.h"
 #include "platform/graphics/Image.h"
 #include "platform/graphics/ImageBuffer.h"
 #include "platform/scheduler/Scheduler.h"
 #include "platform/scroll/ScrollbarTheme.h"
 #include "platform/weborigin/SchemeRegistry.h"
 #include "public/platform/Platform.h"
+#include "public/platform/WebBeginFrameArgs.h"
 #include "public/platform/WebDragData.h"
 #include "public/platform/WebFloatPoint.h"
 #include "public/platform/WebGestureCurve.h"
 #include "public/platform/WebImage.h"
 #include "public/platform/WebLayerTreeView.h"
 #include "public/platform/WebURLRequest.h"
 #include "public/platform/WebVector.h"
 #include "public/web/WebAXObject.h"
 #include "public/web/WebActiveWheelFlingParameters.h"
 #include "public/web/WebAutofillClient.h"
-#include "public/web/WebBeginFrameArgs.h"
 #include "public/web/WebFrameClient.h"
 #include "public/web/WebHitTestResult.h"
 #include "public/web/WebInputElement.h"
 #include "public/web/WebMediaPlayerAction.h"
 #include "public/web/WebNode.h"
 #include "public/web/WebPlugin.h"
 #include "public/web/WebPluginAction.h"
 #include "public/web/WebRange.h"
 #include "public/web/WebTextInputInfo.h"
 #include "public/web/WebViewClient.h"
@@ skipping 4140 matching lines @@
     const PageScaleConstraints& constraints = m_pageScaleConstraintsSet.pageDefinedConstraints();
 
     if (!mainFrameImpl() || !mainFrameImpl()->frameView())
         return false;
 
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 } // namespace blink