Implement will-change-based GPU rasterization hint

Source/core/rendering/compositing/CompositingReasonFinder.cpp

 // Copyright 2014 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 "config.h"
 #include "core/rendering/compositing/CompositingReasonFinder.h"
 
 #include "CSSPropertyNames.h"
 #include "HTMLNames.h"
 #include "core/animation/ActiveAnimations.h"
@@ skipping 245 matching lines @@
     return !!layer->scrollParent();
 }
 
 bool CompositingReasonFinder::requiresCompositingForOutOfFlowClipping(const RenderLayer* layer) const
 {
     return m_renderView.compositorDrivenAcceleratedScrollingEnabled() && layer->isUnclippedDescendant();
 }
 
 bool CompositingReasonFinder::requiresCompositingForWillChange(const RenderObject* renderer) const
 {
-    return renderer->style()->hasWillChangeCompositingHint();
+    if (renderer->style()->hasWillChangeCompositingHint())
+        return true;
+
+    if (Settings* settings = m_renderView.document().settings()) {
+        if (!settings->acceleratedCompositingForGpuRasterizationHintEnabled())
+            return false;
+    }
+
+    return renderer->style()->hasWillChangeGpuRasterizationHint();
 }
 
 bool CompositingReasonFinder::isViewportConstrainedFixedOrStickyLayer(const RenderLayer* layer)
 {
     if (layer->renderer()->isStickyPositioned())
         return !layer->enclosingOverflowClipLayer(ExcludeSelf);
 
     if (layer->renderer()->style()->position() != FixedPosition)
         return false;
 
@@ skipping 107 matching lines @@
 
     return true;
 }
 
 bool CompositingReasonFinder::requiresCompositingForOverflowScrolling(const RenderLayer* layer) const
 {
     return layer->needsCompositedScrolling();
 }
 
 }