Replace pinch scrollbars with regular scrollbars.

Source/core/frame/VisualViewport.cpp

Index: Source/core/frame/VisualViewport.cpp
diff --git a/Source/core/frame/VisualViewport.cpp b/Source/core/frame/VisualViewport.cpp
index 95c5d1416348fae715a163656e7097708bdb2ab6..103148f016c14ec913128ebbf1c7570b898d8ca4 100644
--- a/Source/core/frame/VisualViewport.cpp
+++ b/Source/core/frame/VisualViewport.cpp
@@ -48,19 +48,13 @@
 #include "platform/geometry/FloatSize.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/graphics/GraphicsLayerFactory.h"
-#include "platform/scroll/Scrollbar.h"
-#include "platform/scroll/ScrollbarTheme.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebCompositorSupport.h"
 #include "public/platform/WebLayer.h"
 #include "public/platform/WebLayerTreeView.h"
-#include "public/platform/WebScrollbar.h"
-#include "public/platform/WebScrollbarLayer.h"
 
 using blink::WebLayer;
 using blink::WebLayerTreeView;
-using blink::WebScrollbar;
-using blink::WebScrollbarLayer;
 using blink::FrameHost;
 using blink::GraphicsLayer;
 using blink::GraphicsLayerFactory;
@@ -104,10 +98,6 @@ void VisualViewport::setSize(const IntSize& size)
 
     if (m_innerViewportContainerLayer) {
         m_innerViewportContainerLayer->setSize(m_size);
-
-        // Need to re-compute sizes for the overlay scrollbars.
-        setupScrollbar(WebScrollbar::Horizontal);
-        setupScrollbar(WebScrollbar::Vertical);
     }
 
     if (autosizerNeedsUpdating) {
@@ -273,11 +263,9 @@ bool VisualViewport::magnifyScaleAroundAnchor(float magnifyDelta, const FloatPoi
 //  |                   +-- outerViewportContainerLayer (fixed pos container) [frame container layer in DeprecatedPaintLayerCompositor]
 //  |                   |   +-- outerViewportScrollLayer [frame scroll layer in DeprecatedPaintLayerCompositor]
 //  |                   |       +-- content layers ...
-//  |                   +-- horizontal ScrollbarLayer (non-overlay)
-//  |                   +-- verticalScrollbarLayer (non-overlay)
-//  |                   +-- scroll corner (non-overlay)
-//  +- *horizontalScrollbarLayer (overlay)
-//  +- *verticalScrollbarLayer (overlay)
+//  +- horizontalScrollbarLayer
+//  +- verticalScrollbarLayer
+//  +- scroll corner (non-overlay only)
 //
 void VisualViewport::attachToLayerTree(GraphicsLayer* currentLayerTreeRoot, GraphicsLayerFactory* graphicsLayerFactory)
 {
@@ -292,9 +280,7 @@ void VisualViewport::attachToLayerTree(GraphicsLayer* currentLayerTreeRoot, Grap
         return;
 
     if (!m_innerViewportScrollLayer) {
-        ASSERT(!m_overlayScrollbarHorizontal
-            && !m_overlayScrollbarVertical
-            && !m_overscrollElasticityLayer
+        ASSERT(!m_overscrollElasticityLayer
             && !m_pageScaleLayer
             && !m_innerViewportContainerLayer);
 
@@ -304,8 +290,6 @@ void VisualViewport::attachToLayerTree(GraphicsLayer* currentLayerTreeRoot, Grap
         m_overscrollElasticityLayer = GraphicsLayer::create(graphicsLayerFactory, this);
         m_pageScaleLayer = GraphicsLayer::create(graphicsLayerFactory, this);
         m_innerViewportScrollLayer = GraphicsLayer::create(graphicsLayerFactory, this);
-        m_overlayScrollbarHorizontal = GraphicsLayer::create(graphicsLayerFactory, this);
-        m_overlayScrollbarVertical = GraphicsLayer::create(graphicsLayerFactory, this);
 
         ScrollingCoordinator* coordinator = frameHost().page().scrollingCoordinator();
         ASSERT(coordinator);
@@ -324,68 +308,15 @@ void VisualViewport::attachToLayerTree(GraphicsLayer* currentLayerTreeRoot, Grap
         m_innerViewportContainerLayer->addChild(m_overscrollElasticityLayer.get());
         m_overscrollElasticityLayer->addChild(m_pageScaleLayer.get());
         m_pageScaleLayer->addChild(m_innerViewportScrollLayer.get());
-        m_innerViewportContainerLayer->addChild(m_overlayScrollbarHorizontal.get());
-        m_innerViewportContainerLayer->addChild(m_overlayScrollbarVertical.get());
 
         // Ensure this class is set as the scroll layer's ScrollableArea.
         coordinator->scrollableAreaScrollLayerDidChange(this);
-
-        // Setup the inner viewport overlay scrollbars.
-        setupScrollbar(WebScrollbar::Horizontal);
-        setupScrollbar(WebScrollbar::Vertical);
     }
 
     m_innerViewportScrollLayer->removeAllChildren();
     m_innerViewportScrollLayer->addChild(currentLayerTreeRoot);
 }
 
-void VisualViewport::setupScrollbar(WebScrollbar::Orientation orientation)
-{
-    bool isHorizontal = orientation == WebScrollbar::Horizontal;
-    GraphicsLayer* scrollbarGraphicsLayer = isHorizontal ?
-        m_overlayScrollbarHorizontal.get() : m_overlayScrollbarVertical.get();
-    OwnPtr<WebScrollbarLayer>& webScrollbarLayer = isHorizontal ?
-        m_webOverlayScrollbarHorizontal : m_webOverlayScrollbarVertical;
-
-    int thumbThickness = frameHost().settings().pinchOverlayScrollbarThickness();
-    int scrollbarThickness = thumbThickness;
-    int scrollbarMargin = scrollbarThickness;
-
-    // FIXME: Rather than manually creating scrollbar layers, we should create
-    // real scrollbars so we can reuse all the machinery from ScrollbarTheme.
-#if OS(ANDROID)
-    thumbThickness = ScrollbarTheme::theme()->thumbThickness(0);
-    scrollbarThickness = ScrollbarTheme::theme()->scrollbarThickness(RegularScrollbar);
-    scrollbarMargin = ScrollbarTheme::theme()->scrollbarMargin();
-#endif
-
-    if (!webScrollbarLayer) {
-        ScrollingCoordinator* coordinator = frameHost().page().scrollingCoordinator();
-        ASSERT(coordinator);
-        ScrollbarOrientation webcoreOrientation = isHorizontal ? HorizontalScrollbar : VerticalScrollbar;
-        webScrollbarLayer = coordinator->createSolidColorScrollbarLayer(webcoreOrientation, thumbThickness, scrollbarMargin, false);
-
-        webScrollbarLayer->setClipLayer(m_innerViewportContainerLayer->platformLayer());
-
-        // The compositor will control the scrollbar's visibility. Set to invisible by defualt
-        // so scrollbars don't show up in layout tests.
-        webScrollbarLayer->layer()->setOpacity(0);
-
-        scrollbarGraphicsLayer->setContentsToPlatformLayer(webScrollbarLayer->layer());
-        scrollbarGraphicsLayer->setDrawsContent(false);
-    }
-
-    int xPosition = isHorizontal ? 0 : m_innerViewportContainerLayer->size().width() - scrollbarThickness;
-    int yPosition = isHorizontal ? m_innerViewportContainerLayer->size().height() - scrollbarThickness : 0;
-    int width = isHorizontal ? m_innerViewportContainerLayer->size().width() - scrollbarThickness : scrollbarThickness;
-    int height = isHorizontal ? scrollbarThickness : m_innerViewportContainerLayer->size().height() - scrollbarThickness;
-
-    // Use the GraphicsLayer to position the scrollbars.
-    scrollbarGraphicsLayer->setPosition(IntPoint(xPosition, yPosition));
-    scrollbarGraphicsLayer->setSize(IntSize(width, height));
-    scrollbarGraphicsLayer->setContentsRect(IntRect(0, 0, width, height));
-}
-
 void VisualViewport::registerLayersWithTreeView(WebLayerTreeView* layerTreeView) const
 {
     TRACE_EVENT0("blink", "VisualViewport::registerLayersWithTreeView");
@@ -400,15 +331,14 @@ void VisualViewport::registerLayersWithTreeView(WebLayerTreeView* layerTreeView)
     // Get the outer viewport scroll layer.
     WebLayer* scrollLayer = compositor->scrollLayer() ? compositor->scrollLayer()->platformLayer() : 0;
 
-    m_webOverlayScrollbarHorizontal->setScrollLayer(scrollLayer);
-    m_webOverlayScrollbarVertical->setScrollLayer(scrollLayer);
-
     ASSERT(compositor);
     layerTreeView->registerViewportLayers(
         m_overscrollElasticityLayer->platformLayer(),
         m_pageScaleLayer->platformLayer(),
         m_innerViewportScrollLayer->platformLayer(),
         scrollLayer);
+
+    layerTreeView->setHidePinchScrollbarsNearMinScale(false);
 }
 
 void VisualViewport::clearLayersForTreeView(WebLayerTreeView* layerTreeView) const
@@ -528,8 +458,6 @@ IntSize VisualViewport::contentsSize() const
 
 void VisualViewport::invalidateScrollbarRect(Scrollbar*, const IntRect&)
 {
-    // Do nothing. Visual scrollbars live on the compositor thread and will
-    // be updated when the viewport is synced to the CC.
 }
 
 void VisualViewport::setScrollOffset(const IntPoint& offset, ScrollType scrollType)
@@ -554,12 +482,12 @@ GraphicsLayer* VisualViewport::layerForScrolling() const
 
 GraphicsLayer* VisualViewport::layerForHorizontalScrollbar() const
 {
-    return m_overlayScrollbarHorizontal.get();
+    return 0;
 }
 
 GraphicsLayer* VisualViewport::layerForVerticalScrollbar() const
 {
-    return m_overlayScrollbarVertical.get();
+    return 0;
 }
 
 void VisualViewport::paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect& inClip)
@@ -651,10 +579,6 @@ String VisualViewport::debugName(const GraphicsLayer* graphicsLayer)
         name =  "Page Scale Layer";
     } else if (graphicsLayer == m_innerViewportScrollLayer.get()) {
         name =  "Inner Viewport Scroll Layer";
-    } else if (graphicsLayer == m_overlayScrollbarHorizontal.get()) {
-        name =  "Overlay Scrollbar Horizontal Layer";
-    } else if (graphicsLayer == m_overlayScrollbarVertical.get()) {
-        name =  "Overlay Scrollbar Vertical Layer";
     } else if (graphicsLayer == m_rootTransformLayer) {
         name =  "Root Transform Layer";
     } else {