Disentangle updating the ScrollingCoordinator from RenderLayerCompositor

We only need to update the ScrollingCoordinator once at the root of the frame
tree. We shouldn't be poking at it at every level of the recursion.

This CL finally achieves my dream of controlling
RenderLayerCompositor::updateIfNeeded with just the CompositingUpdateType enum.

Review URL: https://codereview.chromium.org/330513002

git-svn-id: svn://svn.chromium.org/blink/trunk@176046 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/frame/FrameView.cpp

@@ -2832,7 +2832,12 @@ void FrameView::updateLayoutAndStyleForPainting()
 
     if (RenderView* view = renderView()) {
         InspectorInstrumentation::willUpdateLayerTree(view->frame());
+
         view->compositor()->updateIfNeededRecursive();
+
+        if (view->compositor()->inCompositingMode() && m_frame->isMainFrame())
+            m_frame->page()->scrollingCoordinator()->updateAfterCompositingChangeIfNeeded();
+
         InspectorInstrumentation::didUpdateLayerTree(view->frame());
     }
 

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

@@ -122,9 +122,12 @@ void ScrollingCoordinator::notifyLayoutUpdated()
     m_shouldScrollOnMainThreadDirty = true;
 }
 
-void ScrollingCoordinator::updateAfterCompositingChange()
+void ScrollingCoordinator::updateAfterCompositingChangeIfNeeded()
 {
-    TRACE_EVENT0("input", "ScrollingCoordinator::updateAfterCompositingChange");
+    if (!shouldUpdateAfterCompositingChange())
+        return;
+
+    TRACE_EVENT0("input", "ScrollingCoordinator::updateAfterCompositingChangeIfNeeded");
 
     if (m_scrollGestureRegionIsDirty) {
         // Compute the region of the page where we can't handle scroll gestures and mousewheel events

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

@@ -64,10 +64,7 @@ public:
     // Called when any frame has done its layout.
     void notifyLayoutUpdated();
 
-    // Should be called after compositing has been updated.
-    void updateAfterCompositingChange();
-
-    bool needsToUpdateAfterCompositingChange() const { return m_scrollGestureRegionIsDirty || m_touchEventTargetRectsAreDirty || frameViewIsDirty(); }
+    void updateAfterCompositingChangeIfNeeded();
 
     void updateHaveWheelEventHandlers();
     void updateHaveScrollEventHandlers();
@@ -132,6 +129,8 @@ protected:
     bool m_shouldScrollOnMainThreadDirty;
 
 private:
+    bool shouldUpdateAfterCompositingChange() const { return m_scrollGestureRegionIsDirty || m_touchEventTargetRectsAreDirty || frameViewIsDirty(); }
+
     void setShouldUpdateScrollLayerPositionOnMainThread(MainThreadScrollingReasons);
 
     bool hasVisibleSlowRepaintViewportConstrainedObjects(FrameView*) const;

third_party/WebKit/Source/core/rendering/compositing/RenderLayerCompositor.cpp

@@ -291,11 +291,7 @@ void RenderLayerCompositor::updateIfNeeded()
     CompositingUpdateType updateType = m_pendingUpdateType;
     m_pendingUpdateType = CompositingUpdateNone;
 
-    if (!hasAcceleratedCompositing())
-        return;
-
-    bool needsToUpdateScrollingCoordinator = scrollingCoordinator() && scrollingCoordinator()->needsToUpdateAfterCompositingChange();
-    if (updateType == CompositingUpdateNone && !needsToUpdateScrollingCoordinator)
+    if (!hasAcceleratedCompositing() || updateType == CompositingUpdateNone)
         return;
 
     RenderLayer* updateRoot = rootRenderLayer();
@@ -366,11 +362,6 @@ void RenderLayerCompositor::updateIfNeeded()
         m_needsUpdateFixedBackground = false;
     }
 
-    // The scrolling coordinator may realize that it needs updating while compositing was being updated in this function.
-    needsToUpdateScrollingCoordinator |= scrollingCoordinator() && scrollingCoordinator()->needsToUpdateAfterCompositingChange();
-    if (needsToUpdateScrollingCoordinator && m_renderView.frame()->isMainFrame() && scrollingCoordinator() && inCompositingMode())
-        scrollingCoordinator()->updateAfterCompositingChange();
-
     for (unsigned i = 0; i < layersNeedingRepaint.size(); i++) {
         RenderLayer* layer = layersNeedingRepaint[i];
         layer->repainter().computeRepaintRectsIncludingNonCompositingDescendants();