Remove unused callback

The transition is broken, and fixing the issue most likely
need different solution/implementation.

Bug: 1148696
Change-Id: I4a164278250f5b6150ac8fc389eda97623e96614
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2537591Reviewed-by: Toni Baržić <tbarzic@chromium.org>
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827313}

ash/root_window_controller.cc

@@ -876,10 +876,8 @@ void RootWindowController::Init(RootWindowType root_window_type) {
     GetSystemModalLayoutManager(nullptr)->CreateModalBackground();
   }
 
-  wallpaper_widget_controller_ = std::make_unique<WallpaperWidgetController>(
-      root_window,
-      base::BindOnce(&RootWindowController::OnFirstWallpaperWidgetSet,
-                     base::Unretained(this)));
+  wallpaper_widget_controller_ =
+      std::make_unique<WallpaperWidgetController>(root_window);
 
   wallpaper_widget_controller_->Init(
       Shell::Get()->session_controller()->IsUserSessionBlocked());
@@ -1246,13 +1244,4 @@ void RootWindowController::OnMenuClosed() {
   shelf_->UpdateVisibilityState();
 }
 
-void RootWindowController::OnFirstWallpaperWidgetSet() {
-  DCHECK(system_wallpaper_.get());
-
-  // Set the system wallpaper color once a wallpaper has been set to ensure the
-  // wallpaper color that might have been set for the Chrome OS boot splash
-  // screen is overriden.
-  system_wallpaper_->SetColor(SK_ColorBLACK);
-}
-
 }  // namespace ash

ash/wallpaper/wallpaper_widget_controller.cc

@@ -25,11 +25,8 @@
 
 namespace ash {
 
-WallpaperWidgetController::WallpaperWidgetController(
-    aura::Window* root_window,
-    base::OnceClosure wallpaper_set_callback)
-    : root_window_(root_window),
-      wallpaper_set_callback_(std::move(wallpaper_set_callback)) {}
+WallpaperWidgetController::WallpaperWidgetController(aura::Window* root_window)
+    : root_window_(root_window) {}
 
 WallpaperWidgetController::~WallpaperWidgetController() {
   widget_->CloseNow();

ash/wallpaper/wallpaper_widget_controller.h

@@ -35,8 +35,7 @@ class WallpaperView;
 class ASH_EXPORT WallpaperWidgetController
     : public ui::ImplicitAnimationObserver {
  public:
-  WallpaperWidgetController(aura::Window* root_window,
-                            base::OnceClosure wallpaper_set_callback);
+  explicit WallpaperWidgetController(aura::Window* root_window);
   ~WallpaperWidgetController() override;
 
   // Initialize the widget. |lock| specifies if the wallpaper should be created
@@ -89,9 +88,6 @@ class ASH_EXPORT WallpaperWidgetController
 
   aura::Window* root_window_;
 
-  // Callback that will be run when |active_widget_| is first set.
-  base::OnceClosure wallpaper_set_callback_;
-
   // The current wallpaper widget.
   std::unique_ptr<views::Widget> widget_;