[ash-md] WIP Added wallpaper color caching.

chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h

Index: chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h
diff --git a/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h b/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h
index b203984f265bea3a0542513487a57dd579fc58bf..151e697795107494bf657e85bfe24dad0002dc05 100644
--- a/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h
+++ b/chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h
@@ -25,6 +25,10 @@
 #include "mojo/public/cpp/bindings/binding.h"
 #include "ui/gfx/image/image_skia.h"
 
+namespace wallpaper {
+class WallpaperColorCache;
+}  // namespace wallpaper
+
 namespace chromeos {
 
 class WallpaperManager
@@ -193,6 +197,8 @@ class WallpaperManager
       std::unique_ptr<gfx::ImageSkia> large_wallpaper_image) override;
   void RecordWallpaperAppType() override;
 
+  // void Foobar();
+
   mojo::Binding<ash::mojom::WallpaperPicker> binding_;
 
   std::unique_ptr<CrosSettings::ObserverSubscription>
@@ -216,6 +222,8 @@ class WallpaperManager
 
   content::NotificationRegistrar registrar_;
 
+  std::unique_ptr<wallpaper::WallpaperColorCache> wallpaper_color_cache_;
+
   base::WeakPtrFactory<WallpaperManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WallpaperManager);