Plumb scroll elasticity layer from Blink to cc

Implement the 4-argument version of registerViewportLayers
for all implementers of WebLayerTreeView.

Add a scroll elasticity layer to cc::LayerTreeHost and through to
cc::LayerTreeHostImpl. These layers are still optional, and most
tests set them to NULL. Once the Blink side that pushes real layers
through is completed, the scroll elasticity layer will be required.

R=enne
TBR=jam
BUG=133097

Review URL: https://codereview.chromium.org/731863009

Cr-Commit-Position: refs/heads/master@{#305260}

cc/trees/layer_tree_host.cc

@@ -197,7 +197,7 @@ LayerTreeHost::~LayerTreeHost() {
   }
 
   // We must clear any pointers into the layer tree prior to destroying it.
-  RegisterViewportLayers(NULL, NULL, NULL);
+  RegisterViewportLayers(NULL, NULL, NULL, NULL);
 
   if (root_layer_.get()) {
     // The layer tree must be destroyed before the layer tree host. We've
@@ -347,11 +347,12 @@ void LayerTreeHost::FinishCommitOnImplThread(LayerTreeHostImpl* host_impl) {
   sync_tree->set_has_transparent_background(has_transparent_background_);
 
   if (page_scale_layer_.get() && inner_viewport_scroll_layer_.get()) {
-    sync_tree->SetViewportLayersFromIds(page_scale_layer_->id(),
-                                        inner_viewport_scroll_layer_->id(),
-                                        outer_viewport_scroll_layer_.get()
-                                            ? outer_viewport_scroll_layer_->id()
-                                            : Layer::INVALID_ID);
+    sync_tree->SetViewportLayersFromIds(
+        overscroll_elasticity_layer_.get() ? overscroll_elasticity_layer_->id()
+                                           : Layer::INVALID_ID,
+        page_scale_layer_->id(), inner_viewport_scroll_layer_->id(),
+        outer_viewport_scroll_layer_.get() ? outer_viewport_scroll_layer_->id()
+                                           : Layer::INVALID_ID);
   } else {
     sync_tree->ClearViewportLayers();
   }
@@ -1288,9 +1289,11 @@ gfx::Size LayerTreeHost::GetUIResourceSize(UIResourceId uid) const {
 }
 
 void LayerTreeHost::RegisterViewportLayers(
+    scoped_refptr<Layer> overscroll_elasticity_layer,
     scoped_refptr<Layer> page_scale_layer,
     scoped_refptr<Layer> inner_viewport_scroll_layer,
     scoped_refptr<Layer> outer_viewport_scroll_layer) {
+  overscroll_elasticity_layer_ = overscroll_elasticity_layer;
   page_scale_layer_ = page_scale_layer;
   inner_viewport_scroll_layer_ = inner_viewport_scroll_layer;
   outer_viewport_scroll_layer_ = outer_viewport_scroll_layer;

cc/trees/layer_tree_host.h

@@ -179,11 +179,14 @@ class CC_EXPORT LayerTreeHost {
   void SetRootLayer(scoped_refptr<Layer> root_layer);
   Layer* root_layer() { return root_layer_.get(); }
   const Layer* root_layer() const { return root_layer_.get(); }
+  const Layer* overscroll_elasticity_layer() const {
+    return overscroll_elasticity_layer_.get();
+  }
   const Layer* page_scale_layer() const { return page_scale_layer_.get(); }
-  void RegisterViewportLayers(
-      scoped_refptr<Layer> page_scale_layer,
-      scoped_refptr<Layer> inner_viewport_scroll_layer,
-      scoped_refptr<Layer> outer_viewport_scroll_layer);
+  void RegisterViewportLayers(scoped_refptr<Layer> overscroll_elasticity_layer,
+                              scoped_refptr<Layer> page_scale_layer,
+                              scoped_refptr<Layer> inner_viewport_scroll_layer,
+                              scoped_refptr<Layer> outer_viewport_scroll_layer);
   Layer* inner_viewport_scroll_layer() const {
     return inner_viewport_scroll_layer_.get();
   }
@@ -463,6 +466,7 @@ class CC_EXPORT LayerTreeHost {
   int id_;
   bool next_commit_forces_redraw_;
 
+  scoped_refptr<Layer> overscroll_elasticity_layer_;
   scoped_refptr<Layer> page_scale_layer_;
   scoped_refptr<Layer> inner_viewport_scroll_layer_;
   scoped_refptr<Layer> outer_viewport_scroll_layer_;

cc/trees/layer_tree_host_unittest.cc

@@ -1020,8 +1020,8 @@ class LayerTreeHostTestStartPageScaleAnimation : public LayerTreeHostTest {
     layer_tree_host()->root_layer()->AddChild(scroll_layer_);
     // This test requires the page_scale and inner viewport layers to be
     // identified.
-    layer_tree_host()->RegisterViewportLayers(
-        root_layer, scroll_layer_.get(), NULL);
+    layer_tree_host()->RegisterViewportLayers(NULL, root_layer,
+                                              scroll_layer_.get(), NULL);
     layer_tree_host()->SetPageScaleFactorAndLimits(1.f, 0.5f, 2.f);
   }
 
@@ -5512,7 +5512,7 @@ class LayerTreeHostTestCrispUpAfterPinchEnds : public LayerTreeHostTest {
     layer->disable_lcd_text();
     pinch->AddChild(layer);
 
-    layer_tree_host()->RegisterViewportLayers(root, pinch, pinch);
+    layer_tree_host()->RegisterViewportLayers(NULL, root, pinch, pinch);
     layer_tree_host()->SetPageScaleFactorAndLimits(1.f, 1.f, 4.f);
     layer_tree_host()->SetRootLayer(root);
     LayerTreeHostTest::SetupTree();
@@ -5722,7 +5722,7 @@ class LayerTreeHostTestContinuousDrawWhenCreatingVisibleTiles
     layer->disable_lcd_text();
     pinch->AddChild(layer);
 
-    layer_tree_host()->RegisterViewportLayers(root, pinch, pinch);
+    layer_tree_host()->RegisterViewportLayers(NULL, root, pinch, pinch);
     layer_tree_host()->SetPageScaleFactorAndLimits(1.f, 1.f, 4.f);
     layer_tree_host()->SetRootLayer(root);
     LayerTreeHostTest::SetupTree();

cc/trees/layer_tree_host_unittest_scroll.cc

@@ -45,7 +45,8 @@ class LayerTreeHostScrollTestScrollSimple : public LayerTreeHostScrollTest {
     scroll_layer->SetIsContainerForFixedPositionLayers(true);
     scroll_layer->SetScrollClipLayerId(root_layer->id());
     scroll_layer->SetScrollOffset(initial_scroll_);
-    layer_tree_host()->RegisterViewportLayers(root_layer, scroll_layer, NULL);
+    layer_tree_host()->RegisterViewportLayers(NULL, root_layer, scroll_layer,
+                                              NULL);
     PostSetNeedsCommitToMainThread();
   }
 
@@ -122,7 +123,8 @@ class LayerTreeHostScrollTestScrollMultipleRedraw
     scroll_layer_->SetIsContainerForFixedPositionLayers(true);
     scroll_layer_->SetScrollClipLayerId(root_layer->id());
     scroll_layer_->SetScrollOffset(initial_scroll_);
-    layer_tree_host()->RegisterViewportLayers(root_layer, scroll_layer_, NULL);
+    layer_tree_host()->RegisterViewportLayers(NULL, root_layer, scroll_layer_,
+                                              NULL);
     PostSetNeedsCommitToMainThread();
   }
 
@@ -224,8 +226,8 @@ class LayerTreeHostScrollTestScrollAbortedCommit
     root_scroll_layer->SetIsContainerForFixedPositionLayers(true);
     root_layer->AddChild(root_scroll_layer);
 
-    layer_tree_host()->RegisterViewportLayers(
-        root_layer, root_scroll_layer, NULL);
+    layer_tree_host()->RegisterViewportLayers(NULL, root_layer,
+                                              root_scroll_layer, NULL);
     layer_tree_host()->SetPageScaleFactorAndLimits(1.f, 0.01f, 100.f);
   }
 
@@ -407,8 +409,8 @@ class LayerTreeHostScrollTestFractionalScroll : public LayerTreeHostScrollTest {
     root_scroll_layer->SetIsContainerForFixedPositionLayers(true);
     root_layer->AddChild(root_scroll_layer);
 
-    layer_tree_host()->RegisterViewportLayers(
-        root_layer, root_scroll_layer, NULL);
+    layer_tree_host()->RegisterViewportLayers(NULL, root_layer,
+                                              root_scroll_layer, NULL);
     layer_tree_host()->SetPageScaleFactorAndLimits(1.f, 0.01f, 100.f);
   }
 
@@ -510,8 +512,8 @@ class LayerTreeHostScrollTestCaseWithChild : public LayerTreeHostScrollTest {
     expected_scroll_layer_->SetScrollOffset(initial_offset_);
 
     layer_tree_host()->SetRootLayer(root_layer);
-    layer_tree_host()->RegisterViewportLayers(
-        root_layer, root_scroll_layer_, NULL);
+    layer_tree_host()->RegisterViewportLayers(NULL, root_layer,
+                                              root_scroll_layer_, NULL);
     LayerTreeHostScrollTest::SetupTree();
   }
 
@@ -779,8 +781,8 @@ class ImplSidePaintingScrollTestSimple : public ImplSidePaintingScrollTest {
     root_scroll_layer->SetIsContainerForFixedPositionLayers(true);
     root_layer->AddChild(root_scroll_layer);
 
-    layer_tree_host()->RegisterViewportLayers(
-        root_layer, root_scroll_layer, NULL);
+    layer_tree_host()->RegisterViewportLayers(NULL, root_layer,
+                                              root_scroll_layer, NULL);
     layer_tree_host()->SetPageScaleFactorAndLimits(1.f, 0.01f, 100.f);
   }
 
@@ -910,8 +912,8 @@ class ImplSidePaintingScrollTestImplOnlyScroll
     root_scroll_layer->SetIsContainerForFixedPositionLayers(true);
     root_layer->AddChild(root_scroll_layer);
 
-    layer_tree_host()->RegisterViewportLayers(
-        root_layer, root_scroll_layer, NULL);
+    layer_tree_host()->RegisterViewportLayers(NULL, root_layer,
+                                              root_scroll_layer, NULL);
     layer_tree_host()->SetPageScaleFactorAndLimits(1.f, 0.01f, 100.f);
   }
 

cc/trees/layer_tree_impl.cc

@@ -225,8 +225,9 @@ void LayerTreeImpl::PushPropertiesTo(LayerTreeImpl* target_tree) {
 
   if (page_scale_layer_ && inner_viewport_scroll_layer_) {
     target_tree->SetViewportLayersFromIds(
-        page_scale_layer_->id(),
-        inner_viewport_scroll_layer_->id(),
+        overscroll_elasticity_layer_ ? overscroll_elasticity_layer_->id()
+                                     : Layer::INVALID_ID,
+        page_scale_layer_->id(), inner_viewport_scroll_layer_->id(),
         outer_viewport_scroll_layer_ ? outer_viewport_scroll_layer_->id()
                                      : Layer::INVALID_ID);
   } else {
@@ -425,9 +426,11 @@ void LayerTreeImpl::ApplyScrollDeltasSinceBeginMainFrame() {
 }
 
 void LayerTreeImpl::SetViewportLayersFromIds(
+    int overscroll_elasticity_layer_id,
     int page_scale_layer_id,
     int inner_viewport_scroll_layer_id,
     int outer_viewport_scroll_layer_id) {
+  overscroll_elasticity_layer_ = LayerById(overscroll_elasticity_layer_id);
   page_scale_layer_ = LayerById(page_scale_layer_id);
   DCHECK(page_scale_layer_);
 

cc/trees/layer_tree_impl.h

@@ -137,10 +137,14 @@ class CC_EXPORT LayerTreeImpl {
   void SetCurrentlyScrollingLayer(LayerImpl* layer);
   void ClearCurrentlyScrollingLayer();
 
-  void SetViewportLayersFromIds(int page_scale_layer_id,
+  void SetViewportLayersFromIds(int overscroll_elasticity_layer,
+                                int page_scale_layer_id,
                                 int inner_viewport_scroll_layer_id,
                                 int outer_viewport_scroll_layer_id);
   void ClearViewportLayers();
+  LayerImpl* overscroll_elasticity_layer() {
+    return overscroll_elasticity_layer_;
+  }
   LayerImpl* page_scale_layer() { return page_scale_layer_; }
   void ApplySentScrollAndScaleDeltasFromAbortedCommit();
   void ApplyScrollDeltasSinceBeginMainFrame();
@@ -334,6 +338,7 @@ class CC_EXPORT LayerTreeImpl {
   SkColor background_color_;
   bool has_transparent_background_;
 
+  LayerImpl* overscroll_elasticity_layer_;
   LayerImpl* page_scale_layer_;
   LayerImpl* inner_viewport_scroll_layer_;
   LayerImpl* outer_viewport_scroll_layer_;

cc/trees/layer_tree_impl_unittest.cc

@@ -1798,7 +1798,8 @@ TEST_F(LayerTreeImplTest,
   host_impl().active_tree()->SetPageScaleFactorAndLimits(
       page_scale_factor, page_scale_factor, page_scale_factor);
   host_impl().active_tree()->SetRootLayer(root.Pass());
-  host_impl().active_tree()->SetViewportLayersFromIds(1, 1, Layer::INVALID_ID);
+  host_impl().active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 1, 1,
+                                                      Layer::INVALID_ID);
   host_impl().UpdateNumChildrenAndDrawPropertiesForActiveTree();
 
   // Sanity check the scenario we just created.
@@ -2301,7 +2302,8 @@ TEST_F(LayerTreeImplTest, SelectionBoundsForScaledLayers) {
   host_impl().active_tree()->SetPageScaleFactorAndLimits(
       page_scale_factor, page_scale_factor, page_scale_factor);
   host_impl().active_tree()->SetRootLayer(root.Pass());
-  host_impl().active_tree()->SetViewportLayersFromIds(1, 1, Layer::INVALID_ID);
+  host_impl().active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 1, 1,
+                                                      Layer::INVALID_ID);
   host_impl().UpdateNumChildrenAndDrawPropertiesForActiveTree();
 
   // Sanity check the scenario we just created.

content/renderer/gpu/render_widget_compositor.cc

@@ -685,20 +685,40 @@ void RenderWidgetCompositor::registerViewportLayers(
     const blink::WebLayer* innerViewportScrollLayer,
     const blink::WebLayer* outerViewportScrollLayer) {
   layer_tree_host_->RegisterViewportLayers(
+      NULL, static_cast<const cc_blink::WebLayerImpl*>(pageScaleLayer)->layer(),
+      static_cast<const cc_blink::WebLayerImpl*>(innerViewportScrollLayer)
+          ->layer(),
+      // The outer viewport layer will only exist when using pinch virtual
+      // viewports.
+      outerViewportScrollLayer
+          ? static_cast<const cc_blink::WebLayerImpl*>(outerViewportScrollLayer)
+                ->layer()
+          : NULL);
+}
+
+void RenderWidgetCompositor::registerViewportLayers(
+    const blink::WebLayer* overscrollElasticityLayer,
+    const blink::WebLayer* pageScaleLayer,
+    const blink::WebLayer* innerViewportScrollLayer,
+    const blink::WebLayer* outerViewportScrollLayer) {
+  layer_tree_host_->RegisterViewportLayers(
+      static_cast<const cc_blink::WebLayerImpl*>(overscrollElasticityLayer)
+          ->layer(),
       static_cast<const cc_blink::WebLayerImpl*>(pageScaleLayer)->layer(),
       static_cast<const cc_blink::WebLayerImpl*>(innerViewportScrollLayer)
           ->layer(),
       // The outer viewport layer will only exist when using pinch virtual
       // viewports.
-      outerViewportScrollLayer ? static_cast<const cc_blink::WebLayerImpl*>(
-                                     outerViewportScrollLayer)->layer()
-                               : NULL);
+      outerViewportScrollLayer
+          ? static_cast<const cc_blink::WebLayerImpl*>(outerViewportScrollLayer)
+                ->layer()
+          : NULL);
 }
 
 void RenderWidgetCompositor::clearViewportLayers() {
-  layer_tree_host_->RegisterViewportLayers(scoped_refptr<cc::Layer>(),
-                                           scoped_refptr<cc::Layer>(),
-                                           scoped_refptr<cc::Layer>());
+  layer_tree_host_->RegisterViewportLayers(
+      scoped_refptr<cc::Layer>(), scoped_refptr<cc::Layer>(),
+      scoped_refptr<cc::Layer>(), scoped_refptr<cc::Layer>());
 }
 
 void RenderWidgetCompositor::registerSelection(

content/renderer/gpu/render_widget_compositor.h

@@ -113,6 +113,12 @@ class CONTENT_EXPORT RenderWidgetCompositor
   virtual void finishAllRendering();
   virtual void setDeferCommits(bool defer_commits);
   virtual void registerForAnimations(blink::WebLayer* layer);
+  virtual void registerViewportLayers(
+      const blink::WebLayer* overscrollElasticityLayer,
+      const blink::WebLayer* pageScaleLayer,
+      const blink::WebLayer* innerViewportScrollLayer,
+      const blink::WebLayer* outerViewportScrollLayer) override;
+  // TODO(ccameron): Remove this when Blink no longer calls it.
   virtual void registerViewportLayers(
       const blink::WebLayer* pageScaleLayer,
       const blink::WebLayer* innerViewportScrollLayer,

content/test/web_layer_tree_view_impl_for_testing.cc

@@ -164,22 +164,43 @@ void WebLayerTreeViewImplForTesting::RequestNewOutputSurface(
 }
 
 void WebLayerTreeViewImplForTesting::registerViewportLayers(
+    const blink::WebLayer* overscrollElasticityLayer,
     const blink::WebLayer* pageScaleLayer,
     const blink::WebLayer* innerViewportScrollLayer,
     const blink::WebLayer* outerViewportScrollLayer) {
   layer_tree_host_->RegisterViewportLayers(
+      static_cast<const cc_blink::WebLayerImpl*>(overscrollElasticityLayer)
+          ->layer(),
       static_cast<const cc_blink::WebLayerImpl*>(pageScaleLayer)->layer(),
       static_cast<const cc_blink::WebLayerImpl*>(innerViewportScrollLayer)
           ->layer(),
       // The outer viewport layer will only exist when using pinch virtual
       // viewports.
-      outerViewportScrollLayer ? static_cast<const cc_blink::WebLayerImpl*>(
-                                     outerViewportScrollLayer)->layer()
-                               : NULL);
+      outerViewportScrollLayer
+          ? static_cast<const cc_blink::WebLayerImpl*>(outerViewportScrollLayer)
+                ->layer()
+          : NULL);
+}
+
+void WebLayerTreeViewImplForTesting::registerViewportLayers(
+    const blink::WebLayer* pageScaleLayer,
+    const blink::WebLayer* innerViewportScrollLayer,
+    const blink::WebLayer* outerViewportScrollLayer) {
+  layer_tree_host_->RegisterViewportLayers(
+      NULL, static_cast<const cc_blink::WebLayerImpl*>(pageScaleLayer)->layer(),
+      static_cast<const cc_blink::WebLayerImpl*>(innerViewportScrollLayer)
+          ->layer(),
+      // The outer viewport layer will only exist when using pinch virtual
+      // viewports.
+      outerViewportScrollLayer
+          ? static_cast<const cc_blink::WebLayerImpl*>(outerViewportScrollLayer)
+                ->layer()
+          : NULL);
 }
 
 void WebLayerTreeViewImplForTesting::clearViewportLayers() {
   layer_tree_host_->RegisterViewportLayers(scoped_refptr<cc::Layer>(),
+                                           scoped_refptr<cc::Layer>(),
                                            scoped_refptr<cc::Layer>(),
                                            scoped_refptr<cc::Layer>());
 }

content/test/web_layer_tree_view_impl_for_testing.h

@@ -54,6 +54,12 @@ class WebLayerTreeViewImplForTesting
   virtual void didStopFlinging();
   virtual void finishAllRendering();
   virtual void setDeferCommits(bool defer_commits);
+  virtual void registerViewportLayers(
+      const blink::WebLayer* overscrollElasticityLayer,
+      const blink::WebLayer* pageScaleLayerLayer,
+      const blink::WebLayer* innerViewportScrollLayer,
+      const blink::WebLayer* outerViewportScrollLayer) override;
+  // TODO(ccameron): Remove this when Blink no longer calls it.
   virtual void registerViewportLayers(
       const blink::WebLayer* pageScaleLayerLayer,
       const blink::WebLayer* innerViewportScrollLayer,