Introduce ViewRoot forwarding input/view events to native

content/browser/renderer_host/compositor_impl_android.cc

Index: content/browser/renderer_host/compositor_impl_android.cc
diff --git a/content/browser/renderer_host/compositor_impl_android.cc b/content/browser/renderer_host/compositor_impl_android.cc
index a3b1f9040d242e4c343aad3c37d22d79dace1b91..81cc5392a05e75858571b91b1bfbb8c2d136a7da 100644
--- a/content/browser/renderer_host/compositor_impl_android.cc
+++ b/content/browser/renderer_host/compositor_impl_android.cc
@@ -323,6 +323,7 @@ CompositorImpl::CompositorImpl(CompositorClient* client,
                                gfx::NativeWindow root_window)
     : frame_sink_id_(
           ui::ContextProviderFactory::GetInstance()->AllocateFrameSinkId()),
+      root_layer_(cc::Layer::Create()),
       resource_manager_(root_window),
       device_scale_factor_(1),
       window_(NULL),
@@ -339,11 +340,9 @@ CompositorImpl::CompositorImpl(CompositorClient* client,
       ->RegisterFrameSinkId(frame_sink_id_);
   DCHECK(client);
   DCHECK(root_window);
-  DCHECK(root_window->GetLayer() == nullptr);
-  root_window->SetLayer(cc::Layer::Create());
   readback_layer_tree_ = cc::Layer::Create();
   readback_layer_tree_->SetHideLayerAndSubtree(true);
-  root_window->GetLayer()->AddChild(readback_layer_tree_);
+  root_layer_->AddChild(readback_layer_tree_);
   root_window->AttachCompositor(this);
   CreateLayerTreeHost();
   resource_manager_.Init(host_->GetUIResourceManager());
@@ -351,7 +350,6 @@ CompositorImpl::CompositorImpl(CompositorClient* client,
 
 CompositorImpl::~CompositorImpl() {
   root_window_->DetachCompositor();
-  root_window_->SetLayer(nullptr);
   // Clean-up any surface references.
   SetSurface(NULL);
   ui::ContextProviderFactory::GetInstance()
@@ -372,9 +370,9 @@ void CompositorImpl::SetRootLayer(scoped_refptr<cc::Layer> root_layer) {
     subroot_layer_->RemoveFromParent();
     subroot_layer_ = NULL;
   }
-  if (root_window_->GetLayer()) {
-    subroot_layer_ = root_window_->GetLayer();
-    root_window_->GetLayer()->AddChild(root_layer);
+  if (root_layer.get()) {
+    subroot_layer_ = root_layer;
+    root_layer_->AddChild(root_layer);
   }
 }
 
@@ -439,7 +437,7 @@ void CompositorImpl::CreateLayerTreeHost() {
   params.mutator_host = animation_host_.get();
   host_ = cc::LayerTreeHostInProcess::CreateSingleThreaded(this, &params);
   DCHECK(!host_->IsVisible());
-  host_->GetLayerTree()->SetRootLayer(root_window_->GetLayer());
+  host_->GetLayerTree()->SetRootLayer(root_layer_);
   host_->SetFrameSinkId(frame_sink_id_);
   host_->GetLayerTree()->SetViewportSize(size_);
   SetHasTransparentBackground(false);
@@ -486,7 +484,7 @@ void CompositorImpl::SetWindowBounds(const gfx::Size& size) {
     host_->GetLayerTree()->SetViewportSize(size);
   if (display_)
     display_->Resize(size);
-  root_window_->GetLayer()->SetBounds(size);
+  root_layer_->SetBounds(size);
 }
 
 void CompositorImpl::SetHasTransparentBackground(bool transparent) {
@@ -720,7 +718,7 @@ void CompositorImpl::AttachLayerForReadback(scoped_refptr<cc::Layer> layer) {
 
 void CompositorImpl::RequestCopyOfOutputOnRootLayer(
     std::unique_ptr<cc::CopyOutputRequest> request) {
-  root_window_->GetLayer()->RequestCopyOfOutput(std::move(request));
+  root_layer_->RequestCopyOfOutput(std::move(request));
 }
 
 void CompositorImpl::SetNeedsAnimate() {