Reify view ownership as a message pipe.

mojo/ui/view_provider_app.h

 // Copyright 2015 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.
 
 #ifndef MOJO_UI_VIEW_PROVIDER_APP_H_
 #define MOJO_UI_VIEW_PROVIDER_APP_H_
 
 #include <string>
 
 #include "mojo/common/strong_binding_set.h"
@@ skipping 24 matching lines @@
   void Initialize(mojo::ApplicationImpl* app) override;
   bool ConfigureIncomingConnection(
       mojo::ApplicationConnection* connection) override;
 
   // Called by the ViewProvider to create a view.
   // This method may be called multiple times in the case where the
   // view provider is asked to create multiple view instances.
   //
   // The |view_provider_url| is the connection URL of the view provider request.
   //
-  // Returns true if successful, false if the view could not be created.
-  virtual bool CreateView(
+  // The |view_owner_request| should be attached to the newly created view
+  // and closed or left pending if the view could not be created.
+  //
+  // The |services| parameter is used to receive services from the view
+  // on behalf of the caller.
+  //
+  // The |exposed_services| parameters is used to provide services to
+  // the view from the caller.
+  virtual void CreateView(
       const std::string& view_provider_url,
+      mojo::InterfaceRequest<mojo::ui::ViewOwner> view_owner_request,
       mojo::InterfaceRequest<mojo::ServiceProvider> services,
-      mojo::ServiceProviderPtr exposed_services,
-      const mojo::ui::ViewProvider::CreateViewCallback& callback) = 0;
+      mojo::ServiceProviderPtr exposed_services) = 0;
 
  private:
   class DelegatingViewProvider;
 
   // |InterfaceFactory<mojo::ui::ViewProvider>|:
   void Create(mojo::ApplicationConnection* connection,
               mojo::InterfaceRequest<mojo::ui::ViewProvider> request) override;
 
-  void CreateView(DelegatingViewProvider* provider,
-                  const std::string& view_provider_url,
-                  mojo::InterfaceRequest<mojo::ServiceProvider> services,
-                  mojo::ServiceProviderPtr exposed_services,
-                  const mojo::ui::ViewProvider::CreateViewCallback& callback);
+  void CreateView(
+      DelegatingViewProvider* provider,
+      const std::string& view_provider_url,
+      mojo::InterfaceRequest<mojo::ui::ViewOwner> view_owner_request,
+      mojo::InterfaceRequest<mojo::ServiceProvider> services,
+      mojo::ServiceProviderPtr exposed_services);
 
   mojo::ApplicationImpl* app_impl_ = nullptr;
   mojo::StrongBindingSet<mojo::ui::ViewProvider> bindings_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(ViewProviderApp);
 };
 
 }  // namespace ui
 }  // namespace mojo
 
 #endif  // MOJO_UI_VIEW_PROVIDER_APP_H_