mash: Have chrome set itself as the wallpaper picker.

ash/common/wallpaper/wallpaper_controller.h

Index: ash/common/wallpaper/wallpaper_controller.h
diff --git a/ash/common/wallpaper/wallpaper_controller.h b/ash/common/wallpaper/wallpaper_controller.h
index 2d8ba3937b6503d0c47df121bab666d96c70b934..ac2000f055c68302810668b27999de9a02da0277 100644
--- a/ash/common/wallpaper/wallpaper_controller.h
+++ b/ash/common/wallpaper/wallpaper_controller.h
@@ -56,11 +56,8 @@ class ASH_EXPORT WallpaperController
 
   wallpaper::WallpaperLayout GetWallpaperLayout() const;
 
-  // Sets wallpaper. This is mostly called by WallpaperManager to set
-  // the default or user selected custom wallpaper.
-  // Returns true if new image was actually set. And false when duplicate set
-  // request detected.
-  bool SetWallpaperImage(const gfx::ImageSkia& image,
+  // Sets the wallpaper and alerts observers of changes.
+  void SetWallpaperImage(const gfx::ImageSkia& image,
                          wallpaper::WallpaperLayout layout);
 
   // Creates an empty wallpaper. Some tests require a wallpaper widget is ready
@@ -106,6 +103,7 @@ class ASH_EXPORT WallpaperController
   void OpenSetWallpaperPage();
 
   // mojom::WallpaperController overrides:
+  void SetWallpaperPicker(mojom::WallpaperPickerPtr picker) override;
   void SetWallpaper(const SkBitmap& wallpaper,
                     wallpaper::WallpaperLayout layout) override;
 
@@ -131,6 +129,9 @@ class ASH_EXPORT WallpaperController
 
   WallpaperMode wallpaper_mode_;
 
+  // Wallpaper picker interface in chrome browser, used to open the picker.
+  mojom::WallpaperPickerPtr wallpaper_picker_;
+
   // Bindings for the WallpaperController interface.
   mojo::BindingSet<mojom::WallpaperController> bindings_;