Set the proper size of WallpaperViewShield

During the debug, I've just come to realize that the shield layer
of the wallpaper view is zero-sized; so it does not make any
visual effects. It needs to set bounds on creation.

Bug: 1036804
Test: manually
Change-Id: Ifa2dea70424355db12741f7d4bf41b8b3ce8bffa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2080885Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Commit-Queue: Jun Mukai <mukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745701}

ash/wallpaper/wallpaper_view.cc

@@ -95,6 +95,7 @@ void WallpaperView::SetLockShieldEnabled(bool enabled) {
     shield_view_->SetPaintToLayer(ui::LAYER_SOLID_COLOR);
     shield_view_->layer()->SetColor(SK_ColorBLACK);
     shield_view_->layer()->SetName("WallpaperViewShield");
+    shield_view_->SetBoundsRect(parent()->GetLocalBounds());
   } else {
     DCHECK(shield_view_);
     parent()->RemoveChildView(shield_view_);
@@ -110,6 +111,11 @@ bool WallpaperView::OnMousePressed(const ui::MouseEvent& event) {
   return true;
 }
 
+void WallpaperView::OnBoundsChanged(const gfx::Rect& previous_bounds) {
+  if (shield_view_)
+    shield_view_->SetBoundsRect(parent()->GetLocalBounds());
+}
+
 void WallpaperView::ShowContextMenuForViewImpl(views::View* source,
                                                const gfx::Point& point,
                                                ui::MenuSourceType source_type) {

ash/wallpaper/wallpaper_view.h

@@ -38,6 +38,7 @@ class WallpaperView : public WallpaperBaseView,
   // views::View:
   const char* GetClassName() const override;
   bool OnMousePressed(const ui::MouseEvent& event) override;
+  void OnBoundsChanged(const gfx::Rect& previous_bounds) override;
 
   // views::ContextMenuController:
   void ShowContextMenuForViewImpl(views::View* source,