mash: Migrate wallpaper controllers to ash/common.

ash/common/wm_shell.h

Index: ash/common/wm_shell.h
diff --git a/ash/common/wm_shell.h b/ash/common/wm_shell.h
index bf5b830641778281f2227790eda0c534f0c2fc69..1451db730a04ddff7c2e7877553a8ccbd4ff9c46 100644
--- a/ash/common/wm_shell.h
+++ b/ash/common/wm_shell.h
@@ -18,6 +18,10 @@
 #include "base/observer_list.h"
 #include "ui/base/ui_base_types.h"
 
+namespace base {
+class SequencedWorkerPool;
+}
+
 namespace display {
 class Display;
 class ManagedDisplayInfo;
@@ -57,6 +61,7 @@ class ShellObserver;
 class SystemTrayDelegate;
 class SystemTrayNotifier;
 class ToastManager;
+class WallpaperController;
 class WallpaperDelegate;
 class WindowCycleController;
 class WindowCycleEventFilter;
@@ -145,6 +150,10 @@ class ASH_EXPORT WmShell {
 
   ToastManager* toast_manager() { return toast_manager_.get(); }
 
+  WallpaperController* wallpaper_controller() {
+    return wallpaper_controller_.get();
+  }
+
   WallpaperDelegate* wallpaper_delegate() { return wallpaper_delegate_.get(); }
 
   WindowCycleController* window_cycle_controller() {
@@ -352,6 +361,8 @@ class ASH_EXPORT WmShell {
   // True if any touch points are down.
   virtual bool IsTouchDown() = 0;
 
+  virtual base::SequencedWorkerPool* GetBlockingPool() = 0;
+
 #if defined(OS_CHROMEOS)
   LogoutConfirmationController* logout_confirmation_controller() {
     return logout_confirmation_controller_.get();
@@ -420,6 +431,7 @@ class ASH_EXPORT WmShell {
   std::unique_ptr<SystemTrayNotifier> system_tray_notifier_;
   std::unique_ptr<SystemTrayDelegate> system_tray_delegate_;
   std::unique_ptr<ToastManager> toast_manager_;
+  std::unique_ptr<WallpaperController> wallpaper_controller_;
   std::unique_ptr<WallpaperDelegate> wallpaper_delegate_;
   std::unique_ptr<WindowCycleController> window_cycle_controller_;
   std::unique_ptr<WindowSelectorController> window_selector_controller_;