Communicate whether passive event listeners exist to cc.

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 52 matching lines @@
 #include "public/platform/WebScrollbarThemeGeometry.h"
 #include "public/platform/WebScrollbarThemePainter.h"
 #include "wtf/text/StringBuilder.h"
 
 using blink::WebLayer;
 using blink::WebLayerPositionConstraint;
 using blink::WebRect;
 using blink::WebScrollbarLayer;
 using blink::WebVector;
 
+namespace blink {
+
 namespace {
 
 WebLayer* toWebLayer(blink::GraphicsLayer* layer)
 {
     return layer ? layer->platformLayer() : nullptr;
 }
 
+WebEventListenerProperties webEventListenerProperties(EventHandlerRegistry::EventHandlerClass blockingClass, EventHandlerRegistry::EventHandlerClass passiveClass, Page* page)
+{
+    WebEventListenerProperties result = WebEventListenerProperties::Nothing;
+    if (page->frameHost().eventHandlerRegistry().hasEventHandlers(blockingClass))
+        result |= WebEventListenerProperties::Blocking;
+    if (page->frameHost().eventHandlerRegistry().hasEventHandlers(passiveClass))
+        result |= WebEventListenerProperties::Passive;
+    return result;
+}
+
 } // namespace
 
-namespace blink {
-
 PassOwnPtrWillBeRawPtr<ScrollingCoordinator> ScrollingCoordinator::create(Page* page)
 {
     return adoptPtrWillBeNoop(new ScrollingCoordinator(page));
 }
 
 ScrollingCoordinator::ScrollingCoordinator(Page* page)
     : m_page(page)
     , m_scrollGestureRegionIsDirty(false)
     , m_touchEventTargetRectsAreDirty(false)
     , m_shouldScrollOnMainThreadDirty(false)
@@ skipping 579 matching lines @@
         clipParentWebLayer = toWebLayer(parent->compositedLayerMapping()->parentForSublayers());
 
     child->setClipParent(clipParentWebLayer);
 }
 
 void ScrollingCoordinator::willDestroyLayer(PaintLayer* layer)
 {
     m_layersWithTouchRects.remove(layer);
 }
 
-void ScrollingCoordinator::updateHaveWheelEventHandlers()
+void ScrollingCoordinator::updateTouchEventListenerProperties()
 {
     ASSERT(isMainThread());
     ASSERT(m_page);
+    if (!m_page->mainFrame()->isLocalFrame() || !m_page->deprecatedLocalMainFrame()->view())
+        return;
+
+    if (WebLayer* scrollLayer = toWebLayer(m_page->deprecatedLocalMainFrame()->view()->layerForScrolling())) {

[aelias_OOO_until_Jul13, 2016/01/26 19:16:33]

Hmm, on the Blink side we only ever set it on the root scrolling layer.  So the
per-layer tracking and hit-testing stuff this patch has is actually equivalent
to a single root layer enum.  I see that was also the case with the wheel event
properties already.

When the slimming paint v2 change Rick mentioned happens, this code will be
fully deleted and replaced, so this layer-based tracking won't to ever be used
in a meaningful way.  So I'd indeed prefer this to be simplified down to a
global now.  Also, please replace the existing layer wheel event listener stuff
with a global.

[dtapuska, 2016/01/29 21:46:41]

Done.

+        scrollLayer->setTouchEventListenerProperties(webEventListenerProperties(EventHandlerRegistry::TouchEvent, EventHandlerRegistry::TouchEventPassive, m_page));
+    }
+}
+
+void ScrollingCoordinator::updateWheelEventListenerProperties()
+{
+    ASSERT(isMainThread());
+    ASSERT(m_page);
     if (!m_page->mainFrame()->isLocalFrame() || !m_page->deprecatedLocalMainFrame()->view())
         return;
 
     if (WebLayer* scrollLayer = toWebLayer(m_page->deprecatedLocalMainFrame()->view()->layerForScrolling())) {
-        bool haveHandlers = m_page->frameHost().eventHandlerRegistry().hasEventHandlers(EventHandlerRegistry::WheelEvent);
-        scrollLayer->setHaveWheelEventHandlers(haveHandlers);
+        scrollLayer->setWheelEventListenerProperties(webEventListenerProperties(EventHandlerRegistry::WheelEvent, EventHandlerRegistry::WheelEventPassive, m_page));
     }
 }
 
 void ScrollingCoordinator::updateHaveScrollEventHandlers()
 {
     ASSERT(isMainThread());
     ASSERT(m_page);
     if (!m_page->mainFrame()->isLocalFrame() || !m_page->deprecatedLocalMainFrame()->view())
         return;
 
@@ skipping 250 matching lines @@
 
 void ScrollingCoordinator::frameViewRootLayerDidChange(FrameView* frameView)
 {
     ASSERT(isMainThread());
     ASSERT(m_page);
 
     if (!coordinatesScrollingForFrameView(frameView))
         return;
 
     notifyGeometryChanged();
-    updateHaveWheelEventHandlers();
+    updateTouchEventListenerProperties();
+    updateWheelEventListenerProperties();
     updateHaveScrollEventHandlers();
 }
 
 #if OS(MACOSX)
 void ScrollingCoordinator::handleWheelEventPhase(PlatformWheelEventPhase phase)
 {
     ASSERT(isMainThread());
 
     if (!m_page)
         return;
@@ skipping 108 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