Move have_wheel_event_handlers to WebLayerTreeView.

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

Index: third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.cpp
diff --git a/third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.cpp b/third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.cpp
index 84744848cfe370946fd1b638d8113ee47e8be747..b18b108ff77057ed634fd81e50903ea0de4da478 100644
--- a/third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.cpp
+++ b/third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.cpp
@@ -92,6 +92,7 @@ ScrollingCoordinator::ScrollingCoordinator(Page* page)
     , m_touchEventTargetRectsAreDirty(false)
     , m_shouldScrollOnMainThreadDirty(false)
     , m_wasFrameScrollable(false)
+    , m_webLayerTreeView(nullptr)
     , m_lastMainThreadScrollingReasons(0)
 {
 }
@@ -684,13 +685,10 @@ 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()
@@ -729,6 +727,7 @@ void ScrollingCoordinator::layerTreeViewInitialized(WebLayerTreeView& layerTreeV
         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)
@@ -737,6 +736,7 @@ void ScrollingCoordinator::willCloseLayerTreeView(WebLayerTreeView& layerTreeVie
         layerTreeView.detachCompositorAnimationTimeline(m_programmaticScrollAnimatorTimeline.get());
         m_programmaticScrollAnimatorTimeline.clear();
     }
+    m_webLayerTreeView = nullptr;
 }
 
 void ScrollingCoordinator::willBeDestroyed()