Plumb PinchVirtualViewport layers into CC.

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/gpu/render_widget_compositor.h"
 
 #include <limits>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 471 matching lines @@
 void RenderWidgetCompositor::didStopFlinging() {
   layer_tree_host_->DidStopFlinging();
 }
 
 void RenderWidgetCompositor::registerForAnimations(WebKit::WebLayer* layer) {
   cc::Layer* cc_layer = static_cast<webkit::WebLayerImpl*>(layer)->layer();
   cc_layer->layer_animation_controller()->SetAnimationRegistrar(
       layer_tree_host_->animation_registrar());
 }
 
+void RenderWidgetCompositor::registerViewportLayers(
+    const WebKit::WebLayer* pageScaleLayer,
+    const WebKit::WebLayer* innerViewportScrollLayer,
+    const WebKit::WebLayer* outerViewportScrollLayer) {
+  layer_tree_host_->RegisterViewportLayers(
+      static_cast<const webkit::WebLayerImpl*>(pageScaleLayer)->layer(),
+      // The innerviewport layer will only exist when using pinch.

[enne (OOO), 2013/09/11 20:13:03]

I think it's the outer viewport layer that's optional and not the inner.  The
inner is affected by pinch, but the outer one is not.  So, I'd say the inner one
already exists.

[wjmaclean, 2013/09/12 18:16:47]

Yes, right. I keep forgetting we call the newly created layer "inner" so as not
to have to re-organize the existing layers, but conceptually it's the out
viewport layer that's optional.

+      innerViewportScrollLayer ? static_cast<const webkit::WebLayerImpl*>(
+                                     innerViewportScrollLayer)->layer()
+                               : 0,
+      static_cast<const webkit::WebLayerImpl*>(outerViewportScrollLayer)
+          ->layer());
+}
+
+void RenderWidgetCompositor::clearViewportLayers() {
+  layer_tree_host_->RegisterViewportLayers(scoped_refptr<cc::Layer>(),
+                                           scoped_refptr<cc::Layer>(),
+                                           scoped_refptr<cc::Layer>());
+}
+
 bool RenderWidgetCompositor::compositeAndReadback(
     void *pixels, const WebRect& rect_in_device_viewport) {
   return layer_tree_host_->CompositeAndReadback(pixels,
                                                 rect_in_device_viewport);
 }
 
 void RenderWidgetCompositor::finishAllRendering() {
   layer_tree_host_->FinishAllRendering();
 }
 
@@ skipping 92 matching lines @@
   return RenderThreadImpl::current()->OffscreenContextProviderForMainThread();
 }
 
 scoped_refptr<cc::ContextProvider>
 RenderWidgetCompositor::OffscreenContextProviderForCompositorThread() {
   return RenderThreadImpl::current()->
       OffscreenContextProviderForCompositorThread();
 }
 
 }  // namespace content