Move have_wheel_event_handlers to WebLayerTreeView.

third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.cpp

 /*
  * Copyright (C) 2011 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 74 matching lines @@
 {
     return adoptPtrWillBeNoop(new ScrollingCoordinator(page));
 }
 
 ScrollingCoordinator::ScrollingCoordinator(Page* page)
     : m_page(page)
     , m_scrollGestureRegionIsDirty(false)
     , m_touchEventTargetRectsAreDirty(false)
     , m_shouldScrollOnMainThreadDirty(false)
     , m_wasFrameScrollable(false)
+    , m_webLayerTreeView(nullptr)
     , m_lastMainThreadScrollingReasons(0)
 {
 }
 
 ScrollingCoordinator::~ScrollingCoordinator()
 {
     ASSERT(!m_page);
 }
 
 DEFINE_TRACE(ScrollingCoordinator)
@@ skipping 572 matching lines @@
 
 void ScrollingCoordinator::willDestroyLayer(PaintLayer* layer)
 {
     m_layersWithTouchRects.remove(layer);
 }
 
 void ScrollingCoordinator::updateHaveWheelEventHandlers()
 {
     ASSERT(isMainThread());
     ASSERT(m_page);
-    if (!m_page->mainFrame()->isLocalFrame() || !m_page->deprecatedLocalMainFrame()->view())
+    if (!m_webLayerTreeView)
         return;
 
-    if (WebLayer* scrollLayer = toWebLayer(m_page->deprecatedLocalMainFrame()->view()->layerForScrolling())) {
-        bool haveHandlers = m_page->frameHost().eventHandlerRegistry().hasEventHandlers(EventHandlerRegistry::WheelEvent);
-        scrollLayer->setHaveWheelEventHandlers(haveHandlers);
-    }
+    m_webLayerTreeView->setHaveWheelEventHandlers(m_page->frameHost().eventHandlerRegistry().hasEventHandlers(EventHandlerRegistry::WheelEvent));
 }
 
 void ScrollingCoordinator::updateHaveScrollEventHandlers()
 {
     ASSERT(isMainThread());
     ASSERT(m_page);
     if (!m_page->mainFrame()->isLocalFrame() || !m_page->deprecatedLocalMainFrame()->view())
         return;
 
     // Currently the compositor only cares whether there are scroll handlers anywhere on the page
@@ skipping 18 matching lines @@
     }
 }
 
 void ScrollingCoordinator::layerTreeViewInitialized(WebLayerTreeView& layerTreeView)
 {
     if (RuntimeEnabledFeatures::compositorAnimationTimelinesEnabled() && Platform::current()->isThreadedAnimationEnabled()) {
         ASSERT(Platform::current()->compositorSupport());
         m_programmaticScrollAnimatorTimeline = adoptPtr(Platform::current()->compositorSupport()->createAnimationTimeline());
         layerTreeView.attachCompositorAnimationTimeline(m_programmaticScrollAnimatorTimeline.get());
     }
+    m_webLayerTreeView = &layerTreeView;

[aelias_OOO_until_Jul13, 2016/01/27 23:55:46]

I don't think we should make ScrollingCoordinator hold a pointer to the
layerTreeView.  ScrollingCoordinator::updateHaveWheelEventHandlers() has exactly
one caller, EventHandlerRegistry::notifyHasHandlersChanged().  So please delete
the ScrollingCoordinator methods, and instead change that site to use a path
similar to the one next to it for touch events.

[dtapuska, 2016/01/28 16:23:06]

Done.

 }
 
 void ScrollingCoordinator::willCloseLayerTreeView(WebLayerTreeView& layerTreeView)
 {
     if (m_programmaticScrollAnimatorTimeline) {
         layerTreeView.detachCompositorAnimationTimeline(m_programmaticScrollAnimatorTimeline.get());
         m_programmaticScrollAnimatorTimeline.clear();
     }
+    m_webLayerTreeView = nullptr;
 }
 
 void ScrollingCoordinator::willBeDestroyed()
 {
     ASSERT(m_page);
 
     m_page = nullptr;
     for (const auto& scrollbar : m_horizontalScrollbars)
         GraphicsLayer::unregisterContentsLayer(scrollbar.value->layer());
     for (const auto& scrollbar : m_verticalScrollbars)
@@ skipping 332 matching lines @@
     bool frameIsScrollable = frameView && frameView->isScrollable();
     if (frameIsScrollable != m_wasFrameScrollable)
         return true;
 
     if (WebLayer* scrollLayer = frameView ? toWebLayer(frameView->layerForScrolling()) : nullptr)
         return WebSize(frameView->contentsSize()) != scrollLayer->bounds();
     return false;
 }
 
 } // namespace blink