Merge AcceleratedCompositingForOverflowScroll into PreferCompositingToLCDText.

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 "core/CSSPropertyNames.h"
 #include "core/dom/Document.h"
 #include "core/frame/FrameView.h"
@@ skipping 11 matching lines @@
     updateTriggers();
 }
 
 void CompositingReasonFinder::updateTriggers()
 {
     m_compositingTriggers = 0;
 
     Settings& settings = m_renderView.document().page()->settings();
     if (settings.preferCompositingToLCDTextEnabled()) {
         m_compositingTriggers |= ScrollableInnerFrameTrigger;
+        m_compositingTriggers |= OverflowScrollTrigger;
         m_compositingTriggers |= ViewportConstrainedPositionedTrigger;
     }
-
-    // We map both these settings to universal overlow scrolling.
-    // FIXME: Replace these settings with a generic compositing setting for HighDPI.
-    if (settings.acceleratedCompositingForOverflowScrollEnabled() || settings.compositorDrivenAcceleratedScrollingEnabled())
-        m_compositingTriggers |= OverflowScrollTrigger;
 }
 
 bool CompositingReasonFinder::hasOverflowScrollTrigger() const
 {
     return m_compositingTriggers & OverflowScrollTrigger;
 }
 
 bool CompositingReasonFinder::isMainFrame() const
 {
     // FIXME: LocalFrame::isMainFrame() is probably better.
@@ skipping 119 matching lines @@
 bool CompositingReasonFinder::requiresCompositingForPositionFixed(const RenderLayer* layer) const
 {
     if (!(m_compositingTriggers & ViewportConstrainedPositionedTrigger))
         return false;
     // Don't promote fixed position elements that are descendants of a non-view container, e.g. transformed elements.
     // They will stay fixed wrt the container rather than the enclosing frame.
     return layer->scrollsWithViewport() && m_renderView.frameView()->isScrollable();
 }
 
 }