Remove support for CompositingReasonPositionSticky

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/frame/FrameView.h"
 #include "core/frame/Settings.h"
 #include "core/page/Page.h"
@@ skipping 118 matching lines @@
         if (layer->potentiallyStaleIsUnclippedDescendant())
             directReasons |= CompositingReasonOutOfFlowClipping;
 
         if (layer->scrollParent())
             directReasons |= CompositingReasonOverflowScrollingParent;
 
         if (layer->needsCompositedScrolling())
             directReasons |= CompositingReasonOverflowScrollingTouch;
     }
 
-    if (requiresCompositingForPositionSticky(renderer, layer))
-        directReasons |= CompositingReasonPositionSticky;
-
     if (requiresCompositingForPositionFixed(renderer, layer, 0))
         directReasons |= CompositingReasonPositionFixed;
 
     directReasons |= renderer->additionalCompositingReasons(m_compositingTriggers);
 
     ASSERT(!(directReasons & CompositingReasonComboAllStyleDeterminedReasons));
     return directReasons;
 }
 
 bool CompositingReasonFinder::requiresCompositingForAnimation(RenderStyle* style) const
 {
     if (style->subtreeWillChangeContents())
         return style->isRunningAnimationOnCompositor();
 
     return style->shouldCompositeForCurrentAnimations();
 }
 
-bool CompositingReasonFinder::requiresCompositingForPosition(RenderObject* renderer, const RenderLayer* layer, RenderLayer::ViewportConstrainedNotCompositedReason* viewportConstrainedNotCompositedReason) const
-{
-    return requiresCompositingForPositionSticky(renderer, layer) || requiresCompositingForPositionFixed(renderer, layer, viewportConstrainedNotCompositedReason);
-}
-
-bool CompositingReasonFinder::requiresCompositingForPositionSticky(RenderObject* renderer, const RenderLayer* layer) const
-{
-    if (!(m_compositingTriggers & ViewportConstrainedPositionedTrigger))
-        return false;
-    if (renderer->style()->position() != StickyPosition)
-        return false;
-    // FIXME: This probably isn't correct for accelerated overflow scrolling. crbug.com/361723
-    // Instead it should return false only if the layer is not inside a scrollable region.
-    return !layer->enclosingOverflowClipLayer(ExcludeSelf);
-}
-
 bool CompositingReasonFinder::requiresCompositingForPositionFixed(RenderObject* renderer, const RenderLayer* layer, RenderLayer::ViewportConstrainedNotCompositedReason* viewportConstrainedNotCompositedReason) const
 {
     if (!(m_compositingTriggers & ViewportConstrainedPositionedTrigger))
         return false;
 
     if (renderer->style()->position() != FixedPosition)
         return false;
 
     RenderObject* container = renderer->container();
     // If the renderer is not hooked up yet then we have to wait until it is.
@@ skipping 61 matching lines @@
             if (viewportConstrainedNotCompositedReason)
                 *viewportConstrainedNotCompositedReason = RenderLayer::NotCompositedForBoundsOutOfView;
             return false;
         }
     }
 
     return true;
 }
 
 }