CrOS Status Area: No need to observe shelf config from delegate

Instead, call |UpdateLayout| from the widget itself.

Bug: 1050788
Change-Id: I42be9e98f56df6c04b3662a832050069b1b689c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2053125Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Commit-Queue: Manu Cornet <manucornet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#741095}

ash/system/status_area_widget.cc

@@ -424,6 +424,7 @@ void StatusAreaWidget::OnShelfConfigUpdated() {
   for (TrayBackgroundView* tray_button : tray_buttons_)
     tray_button->UpdateAfterShelfChange();
   UpdateCollapseState();
+  status_area_widget_delegate_->UpdateLayout();
 }
 
 void StatusAreaWidget::UpdateAfterColorModeChange() {

ash/system/status_area_widget_delegate.cc

@@ -84,8 +84,6 @@ StatusAreaWidgetDelegate::StatusAreaWidgetDelegate(Shelf* shelf)
   DCHECK(shelf_);
   set_owned_by_client();  // Deleted by DeleteDelegate().
 
-  ShelfConfig::Get()->AddObserver(this);
-
   // Allow the launcher to surrender the focus to another window upon
   // navigation completion by the user.
   set_allow_deactivate_on_esc(true);
@@ -93,9 +91,7 @@ StatusAreaWidgetDelegate::StatusAreaWidgetDelegate(Shelf* shelf)
   layer()->SetFillsBoundsOpaquely(false);
 }
 
-StatusAreaWidgetDelegate::~StatusAreaWidgetDelegate() {
-  ShelfConfig::Get()->RemoveObserver(this);
-}
+StatusAreaWidgetDelegate::~StatusAreaWidgetDelegate() = default;
 
 void StatusAreaWidgetDelegate::SetFocusCyclerForTesting(
     const FocusCycler* focus_cycler) {
@@ -173,10 +169,6 @@ void StatusAreaWidgetDelegate::DeleteDelegate() {
   delete this;
 }
 
-void StatusAreaWidgetDelegate::OnShelfConfigUpdated() {
-  UpdateLayout();
-}
-
 void StatusAreaWidgetDelegate::UpdateLayout() {
   // Use a grid layout so that the trays can be centered in each cell, and
   // so that the widget gets laid out correctly when tray sizes change.

ash/system/status_area_widget_delegate.h

@@ -20,8 +20,7 @@ class Shelf;
 
 // The View for the status area widget.
 class ASH_EXPORT StatusAreaWidgetDelegate : public views::AccessiblePaneView,
-                                            public views::WidgetDelegate,
-                                            public ShelfConfig::Observer {
+                                            public views::WidgetDelegate {
  public:
   explicit StatusAreaWidgetDelegate(Shelf* shelf);
   ~StatusAreaWidgetDelegate() override;
@@ -54,9 +53,6 @@ class ASH_EXPORT StatusAreaWidgetDelegate : public views::AccessiblePaneView,
   bool CanActivate() const override;
   void DeleteDelegate() override;
 
-  // ShelfConfig::Observer:
-  void OnShelfConfigUpdated() override;
-
   void set_default_last_focusable_child(bool default_last_focusable_child) {
     default_last_focusable_child_ = default_last_focusable_child;
   }