services/ui: Allow injecting the IO thread task runner for gpu channel.

ui/views/mus/window_manager_connection.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 UI_VIEWS_MUS_WINDOW_MANAGER_CONNECTION_H_
 #define UI_VIEWS_MUS_WINDOW_MANAGER_CONNECTION_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 37 matching lines @@
 // WindowManagerConnection is a singleton and should be created early on.
 //
 // TODO(sky): this name is now totally confusing. Come up with a better one.
 class VIEWS_MUS_EXPORT WindowManagerConnection
     : public NON_EXPORTED_BASE(ui::WindowTreeClientDelegate),
       public ScreenMusDelegate,
       public ui::OSExchangeDataProviderFactory::Factory {
  public:
   ~WindowManagerConnection() override;
 
+  // |io_task_runner| is used by the gpu service. If no task runner is provided,
+  // then a new thread is created and used by ui::GpuService.
   static std::unique_ptr<WindowManagerConnection> Create(
       shell::Connector* connector,
-      const shell::Identity& identity);
+      const shell::Identity& identity,
+      scoped_refptr<base::SingleThreadTaskRunner> io_task_runner = nullptr);
   static WindowManagerConnection* Get();
   static bool Exists();
 
   PointerWatcherEventRouter* pointer_watcher_event_router() {
     return pointer_watcher_event_router_.get();
   }
   shell::Connector* connector() { return connector_; }
   ui::GpuService* gpu_service() { return gpu_service_.get(); }
   ui::WindowTreeClient* client() { return client_.get(); }
 
   ui::Window* NewWindow(
       const std::map<std::string, std::vector<uint8_t>>& properties);
 
   NativeWidget* CreateNativeWidgetMus(
       const std::map<std::string, std::vector<uint8_t>>& properties,
       const Widget::InitParams& init_params,
       internal::NativeWidgetDelegate* delegate);
 
   const std::set<ui::Window*>& GetRoots() const;
 
  private:
-  WindowManagerConnection(shell::Connector* connector,
-                          const shell::Identity& identity);
+  WindowManagerConnection(
+      shell::Connector* connector,
+      const shell::Identity& identity,
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner);
 
   // ui::WindowTreeClientDelegate:
   void OnEmbed(ui::Window* root) override;
   void OnDidDestroyClient(ui::WindowTreeClient* client) override;
   void OnPointerEventObserved(const ui::PointerEvent& event,
                               ui::Window* target) override;
 
   // ScreenMusDelegate:
   void OnWindowManagerFrameValuesChanged() override;
   gfx::Point GetCursorScreenPoint() override;
 
   // ui:OSExchangeDataProviderFactory::Factory:
   std::unique_ptr<OSExchangeData::Provider> BuildProvider() override;
 
   shell::Connector* connector_;
   shell::Identity identity_;
   std::unique_ptr<ScreenMus> screen_;
   std::unique_ptr<ui::WindowTreeClient> client_;
   std::unique_ptr<ui::GpuService> gpu_service_;
   std::unique_ptr<PointerWatcherEventRouter> pointer_watcher_event_router_;
   std::unique_ptr<SurfaceContextFactory> compositor_context_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowManagerConnection);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_MUS_WINDOW_MANAGER_CONNECTION_H_