mus: Fix creating the factory for window-tree-client in renderer.

content/renderer/mus/renderer_window_tree_client.h

 // Copyright 2017 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 CONTENT_RENDERER_MUS_RENDERER_WINDOW_TREE_CLIENT_H_
 #define CONTENT_RENDERER_MUS_RENDERER_WINDOW_TREE_CLIENT_H_
 
 #include "base/macros.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "services/ui/common/types.h"
@@ skipping 12 matching lines @@
 class WindowCompositorFrameSinkBinding;
 }
 
 namespace content {
 
 // ui.mojom.WindowTreeClient implementation for RenderWidget. This lives and
 // operates on the renderer's main thread.
 class RendererWindowTreeClient : public ui::mojom::WindowTreeClient {
  public:
   // Creates a RendererWindowTreeClient instance for the RenderWidget instance
-  // associated with |routing_id|. The instance self-destructs when the
-  // connection to mus is lost, or when the window is closed.
-  static void Create(int routing_id);
+  // associated with |routing_id| (if one doesn't already exist). The instance
+  // self-destructs when the connection to mus is lost, or when the window is
+  // closed.
+  static void CreateIfNecessary(int routing_id);
 
   // Destroys the client instance, if one exists. Otherwise, does nothing.
   static void Destroy(int routing_id);
 
   // Returns the RendererWindowTreeClient associated with |routing_id|. Returns
   // nullptr if none exists.
   static RendererWindowTreeClient* Get(int routing_id);
 
   void Bind(ui::mojom::WindowTreeClientRequest request);
 
@@ skipping 101 matching lines @@
   ui::mojom::WindowTreePtr tree_;
   std::unique_ptr<ui::WindowCompositorFrameSinkBinding> pending_frame_sink_;
   mojo::Binding<ui::mojom::WindowTreeClient> binding_;
 
   DISALLOW_COPY_AND_ASSIGN(RendererWindowTreeClient);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MUS_RENDERER_WINDOW_TREE_CLIENT_H_