mash: Migrate wallpaper controllers to ash/common.

ash/common/wallpaper/wallpaper_controller.h

Index: ash/common/wallpaper/wallpaper_controller.h
diff --git a/ash/wallpaper/wallpaper_controller.h b/ash/common/wallpaper/wallpaper_controller.h
similarity index 93%
rename from ash/wallpaper/wallpaper_controller.h
rename to ash/common/wallpaper/wallpaper_controller.h
index b469e37b1c11994304d6c227e8eda0b3af061dc1..f7498536d2875e0ff19f6dd70d588b8898e83ddd 100644
--- a/ash/wallpaper/wallpaper_controller.h
+++ b/ash/common/wallpaper/wallpaper_controller.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef ASH_WALLPAPER_WALLPAPER_CONTROLLER_H_
-#define ASH_WALLPAPER_WALLPAPER_CONTROLLER_H_
+#ifndef ASH_COMMON_WALLPAPER_WALLPAPER_CONTROLLER_H_
+#define ASH_COMMON_WALLPAPER_WALLPAPER_CONTROLLER_H_
 
 #include <memory>
 
@@ -16,7 +16,7 @@
 #include "ui/gfx/image/image_skia.h"
 
 namespace base {
-class SequencedWorkerPool;
+class TaskRunner;
 }
 
 namespace wallpaper {
@@ -33,7 +33,7 @@ class ASH_EXPORT WallpaperController : public WmDisplayObserver,
  public:
   enum WallpaperMode { WALLPAPER_NONE, WALLPAPER_IMAGE };
 
-  explicit WallpaperController(base::SequencedWorkerPool* blocking_pool);
+  explicit WallpaperController(base::TaskRunner* task_runner);
   ~WallpaperController() override;
 
   // Add/Remove observers.
@@ -124,11 +124,11 @@ class ASH_EXPORT WallpaperController : public WmDisplayObserver,
 
   int wallpaper_reload_delay_;
 
-  base::SequencedWorkerPool* blocking_pool_;
+  base::TaskRunner* task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(WallpaperController);
 };
 
 }  // namespace ash
 
-#endif  // ASH_WALLPAPER_WALLPAPER_CONTROLLER_H_
+#endif  // ASH_COMMON_WALLPAPER_WALLPAPER_CONTROLLER_H_