Add development Blink setting for impl-side rubber-banding

Add a flag to indicate if the compositor thread is performing the
Mac overscroll rubber-band bounce effect.

This is false by default and will be set to true by
--enable-threaded-event-handling-mac until developement is finished,
whereupon it will be true by default and removed.

BUG=133097
TBR=dglazkov

Review URL: https://codereview.chromium.org/722353002

git-svn-id: svn://svn.chromium.org/blink/trunk@185385 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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

@@ -1673,6 +1673,11 @@ bool FrameView::isRubberBandInProgress() const
     return false;
 }
 
+bool FrameView::rubberBandingOnCompositorThread() const
+{
+    return m_frame->settings()->rubberBandingOnCompositorThread();
+}
+
 HostWindow* FrameView::hostWindow() const
 {
     Page* page = frame().page();

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

@@ -163,6 +163,7 @@ public:
 
     void setScrollPosition(const DoublePoint&, ScrollBehavior = ScrollBehaviorInstant);
     virtual bool isRubberBandInProgress() const override;
+    virtual bool rubberBandingOnCompositorThread() const override;
     void setScrollPositionNonProgrammatically(const IntPoint&);
 
     // This is different than visibleContentRect() in that it ignores negative (or overly positive)

third_party/WebKit/Source/core/frame/Settings.in

@@ -224,6 +224,11 @@ pinchVirtualViewportEnabled initial=false
 useSolidColorScrollbars initial=false
 pinchOverlayScrollbarThickness type=int, initial=0
 
+# The rubber-band overscroll effect is implemented in Blink and is being moved
+# to the compositor thread. This will be set to true and eventually removed.
+# crbug.com/133097
+rubberBandingOnCompositorThread initial=false
+
 mainFrameClipsContent initial=true
 
 

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

@@ -901,7 +901,7 @@ bool RenderLayerCompositor::requiresScrollCornerLayer() const
 void RenderLayerCompositor::updateOverflowControlsLayers()
 {
 #if USE(RUBBER_BANDING)
-    if (m_renderView.frame()->isLocalRoot()) {
+    if (m_renderView.frame()->isLocalRoot() && !m_renderView.document().settings()->rubberBandingOnCompositorThread()) {
         if (!m_layerForOverhangShadow) {
             m_layerForOverhangShadow = GraphicsLayer::create(graphicsLayerFactory(), this);
             OverscrollTheme::theme()->setUpOverhangShadowLayer(m_layerForOverhangShadow.get());

third_party/WebKit/Source/platform/mac/ScrollAnimatorMac.mm

@@ -1080,7 +1080,7 @@ bool ScrollAnimatorMac::handleWheelEvent(const PlatformWheelEvent& wheelEvent)
 {
     m_haveScrolledSincePageLoad = true;
 
-    if (!wheelEvent.hasPreciseScrollingDeltas() || !rubberBandingEnabledForSystem())
+    if (!wheelEvent.hasPreciseScrollingDeltas() || !rubberBandingEnabledForSystem() || m_scrollableArea->rubberBandingOnCompositorThread())
         return ScrollAnimator::handleWheelEvent(wheelEvent);
 
     // FIXME: This is somewhat roundabout hack to allow forwarding wheel events

third_party/WebKit/Source/platform/scroll/ScrollableArea.h

@@ -185,6 +185,7 @@ public:
     virtual IntRect scrollableAreaBoundingBox() const = 0;
 
     virtual bool isRubberBandInProgress() const { return false; }
+    virtual bool rubberBandingOnCompositorThread() const { return false; }
 
     virtual bool scrollAnimatorEnabled() const { return false; }
 

third_party/WebKit/Source/web/WebSettingsImpl.cpp

@@ -251,6 +251,11 @@ void WebSettingsImpl::setRootLayerScrolls(bool rootLayerScrolls)
     m_settings->setRootLayerScrolls(rootLayerScrolls);
 }
 
+void WebSettingsImpl::setRubberBandingOnCompositorThread(bool rubberBandingOnCompositorThread)
+{
+    m_settings->setRubberBandingOnCompositorThread(rubberBandingOnCompositorThread);
+}
+
 void WebSettingsImpl::setClobberUserAgentInitialScaleQuirk(bool clobberUserAgentInitialScaleQuirk)
 {
     m_clobberUserAgentInitialScaleQuirk = clobberUserAgentInitialScaleQuirk;

third_party/WebKit/Source/web/WebSettingsImpl.h

@@ -135,6 +135,7 @@ public:
     virtual void setRenderVSyncNotificationEnabled(bool) override;
     virtual void setReportScreenSizeInPhysicalPixelsQuirk(bool) override;
     virtual void setRootLayerScrolls(bool) override;
+    virtual void setRubberBandingOnCompositorThread(bool) override;
     virtual void setSansSerifFontFamily(const WebString&, UScriptCode = USCRIPT_COMMON) override;
     virtual void setSelectTrailingWhitespaceEnabled(bool override);
     virtual void setSelectionIncludesAltImageText(bool) override;

third_party/WebKit/public/web/WebSettings.h

@@ -186,6 +186,7 @@ public:
     virtual void setRenderVSyncNotificationEnabled(bool) = 0;
     virtual void setReportScreenSizeInPhysicalPixelsQuirk(bool) = 0;
     virtual void setRootLayerScrolls(bool) = 0;
+    virtual void setRubberBandingOnCompositorThread(bool) = 0;
     virtual void setSansSerifFontFamily(const WebString&, UScriptCode = USCRIPT_COMMON) = 0;
     virtual void setSelectTrailingWhitespaceEnabled(bool) = 0;
     virtual void setSelectionIncludesAltImageText(bool) = 0;