Set up clip and scroll parents on the blink side.

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 270 matching lines @@
             scrollbarGraphicsLayer->setContentsOpaque(isMainFrame && isOpaqueScrollbar);
         scrollbarLayer->layer()->setOpaque(scrollbarGraphicsLayer->contentsOpaque());
 
         setupScrollbarLayer(scrollbarGraphicsLayer, scrollbarLayer, scrollingWebLayerForScrollableArea(scrollableArea));
     } else
         removeWebScrollbarLayer(scrollableArea, orientation);
 }
 
 bool ScrollingCoordinator::scrollableAreaScrollLayerDidChange(ScrollableArea* scrollableArea)
 {
+    TRACE_EVENT_INSTANT2("comp-scroll", "ScrollingCoordinator::scrollableAreaScrollLayerDidChange",
+        "width", scrollableArea->scrollableAreaBoundingBox().width(),
+        "height", scrollableArea->scrollableAreaBoundingBox().height());
+
     GraphicsLayer* scrollLayer = scrollLayerForScrollableArea(scrollableArea);
     if (scrollLayer) {
         bool isMainFrame = isForMainFrame(scrollableArea);
         scrollLayer->setScrollableArea(scrollableArea, isMainFrame);
     }
 
     WebLayer* webLayer = scrollingWebLayerForScrollableArea(scrollableArea);
     if (webLayer) {
         webLayer->setScrollable(true);
         webLayer->setScrollPosition(IntPoint(scrollableArea->scrollPosition() - scrollableArea->minimumScrollPosition()));
@@ skipping 97 matching lines @@
     if (m_page->mainFrame()->view()->needsLayout())
         return;
 
     TRACE_EVENT0("input", "ScrollingCoordinator::touchEventTargetRectsDidChange");
 
     LayerHitTestRects touchEventTargetRects;
     computeTouchEventTargetRects(touchEventTargetRects);
     setTouchEventTargetRects(touchEventTargetRects);
 }
 
+void ScrollingCoordinator::updateScrollParentForLayer(RenderLayer* child, RenderLayer* parent)
+{
+    if (!child || !child->backing())
+        return;
+
+    WebLayer* childWebLayer = scrollingWebLayerForGraphicsLayer(child->layerForScrollChild());
+    if (!childWebLayer)
+        return;
+
+    WebLayer* scrollParentWebLayer = 0;
+    if (parent && parent->backing())
+        scrollParentWebLayer = scrollingWebLayerForGraphicsLayer(parent->backing()->parentForSublayers());
+
+    TRACE_EVENT_INSTANT2("comp-scroll2", "ScrollingCoordinator::updateScrollParentForLayer",

[enne (OOO), 2013/08/22 20:54:30]

Would this trace event be better on the cc side where you could only do it when
the scroll parent changed? Same question for a bunch of other places.

Also, comp-scroll2??

+        "childId", childWebLayer->id(),
+        "ancestorId", scrollParentWebLayer ? scrollParentWebLayer->id() : -1);

[enne (OOO), 2013/08/22 20:54:30]

Ids start at 1, so you could say 0.

+
+    childWebLayer->setScrollParent(scrollParentWebLayer);
+}
+
+void ScrollingCoordinator::updateClipParentForLayer(RenderLayer* child, RenderLayer* parent)
+{
+    if (!child || !child->backing())
+        return;
+
+    WebLayer* childWebLayer = scrollingWebLayerForGraphicsLayer(child->backing()->graphicsLayer());
+    if (!childWebLayer)
+        return;
+
+    WebLayer* clipParentWebLayer = 0;
+    if (parent && parent->backing())
+        clipParentWebLayer = scrollingWebLayerForGraphicsLayer(parent->backing()->parentForSublayers());
+
+    TRACE_EVENT_INSTANT2("comp-scroll", "ScrollingCoordinator::updateClipParentForLayer",
+        "childId", childWebLayer->id(),
+        "ancestorId", clipParentWebLayer ? clipParentWebLayer->id() : -1);
+
+    childWebLayer->setClipParent(clipParentWebLayer);
+}
+
 void ScrollingCoordinator::setWheelEventHandlerCount(unsigned count)
 {
     if (WebLayer* scrollLayer = scrollingWebLayerForScrollableArea(m_page->mainFrame()->view()))
         scrollLayer->setHaveWheelEventHandlers(count > 0);
 }
 
 void ScrollingCoordinator::recomputeWheelEventHandlerCountForFrameView(FrameView* frameView)
 {
     UNUSED_PARAM(frameView);
     setWheelEventHandlerCount(computeCurrentWheelEventHandlerCount());
 }
 
 void ScrollingCoordinator::setShouldUpdateScrollLayerPositionOnMainThread(MainThreadScrollingReasons reasons)
 {
-    if (WebLayer* scrollLayer = scrollingWebLayerForScrollableArea(m_page->mainFrame()->view()))
+    if (WebLayer* scrollLayer = scrollingWebLayerForScrollableArea(m_page->mainFrame()->view())) {
+        TRACE_EVENT_INSTANT2("impl-scroll", "ScrollingCoordinator::setShouldUpdateScrollLayerPositionOnMainThread",
+            "layerId", scrollLayer->id(),
+            "reasons", reasons);
         scrollLayer->setShouldScrollOnMainThread(reasons);
+    }
 }
 
 void ScrollingCoordinator::pageDestroyed()
 {
     ASSERT(m_page);
     m_page = 0;
 }
 
 bool ScrollingCoordinator::coordinatesScrollingForFrameView(FrameView* frameView) const
 {
@@ skipping 294 matching lines @@
         stringBuilder.resize(stringBuilder.length() - 2);
     return stringBuilder.toString();
 }
 
 String ScrollingCoordinator::mainThreadScrollingReasonsAsText() const
 {
     return mainThreadScrollingReasonsAsText(mainThreadScrollingReasons());
 }
 
 } // namespace WebCore