Reify view ownership as a message pipe.

services/ui/view_manager/view_host_impl.h

Index: services/ui/view_manager/view_host_impl.h
diff --git a/services/ui/view_manager/view_host_impl.h b/services/ui/view_manager/view_host_impl.h
index 907c8f1353a081935880afe21b36bfd7ab75a1b5..2ed54f613a875eb8885194ad041f1ab553ee1e27 100644
--- a/services/ui/view_manager/view_host_impl.h
+++ b/services/ui/view_manager/view_host_impl.h
@@ -7,36 +7,35 @@
 
 #include "base/macros.h"
 #include "mojo/common/binding_set.h"
-#include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/services/ui/views/interfaces/views.mojom.h"
-#include "services/ui/view_manager/view_registry.h"
-#include "services/ui/view_manager/view_state.h"
 
 namespace view_manager {
 
+class ViewRegistry;
+class ViewState;
+
 // ViewHost interface implementation.
 // This object is owned by its associated ViewState.
-class ViewHostImpl : public mojo::ui::ViewHost, public mojo::ServiceProvider {
+class ViewHostImpl : public mojo::ui::ViewHost,
+                     public mojo::ui::ViewOwner,
+                     public mojo::ServiceProvider {
  public:
-  ViewHostImpl(ViewRegistry* registry,
-               ViewState* state,
-               mojo::InterfaceRequest<mojo::ui::ViewHost> view_host_request);
+  ViewHostImpl(ViewRegistry* registry, ViewState* state);
   ~ViewHostImpl() override;
 
-  void set_view_host_connection_error_handler(const base::Closure& handler) {
-    binding_.set_connection_error_handler(handler);
-  }
-
  private:
   // |ViewHost|:
+  void GetToken(const mojo::ui::ViewHost::GetTokenCallback& callback) override;
   void GetServiceProvider(mojo::InterfaceRequest<mojo::ServiceProvider>
                               service_provider_request) override;
   void CreateScene(
       mojo::InterfaceRequest<mojo::gfx::composition::Scene> scene) override;
   void RequestLayout() override;
   void AddChild(uint32_t child_key,
-                mojo::ui::ViewTokenPtr child_view_token) override;
-  void RemoveChild(uint32_t child_key) override;
+                mojo::ui::ViewOwnerPtr child_view_owner) override;
+  void RemoveChild(uint32_t child_key,
+                   mojo::InterfaceRequest<mojo::ui::ViewOwner>
+                       transferred_view_owner_request) override;
   void LayoutChild(uint32_t child_key,
                    mojo::ui::ViewLayoutParamsPtr child_layout_params,
                    const LayoutChildCallback& callback) override;
@@ -47,7 +46,6 @@ class ViewHostImpl : public mojo::ui::ViewHost, public mojo::ServiceProvider {
 
   ViewRegistry* const registry_;
   ViewState* const state_;
-  mojo::Binding<mojo::ui::ViewHost> binding_;
   mojo::BindingSet<mojo::ServiceProvider> service_provider_bindings_;
 
   DISALLOW_COPY_AND_ASSIGN(ViewHostImpl);