Accessibility checks shelf crash fix

Bug: 819350
Change-Id: I244117aa25f5da865af5d3d8492079337b3f9696
Reviewed-on: https://chromium-review.googlesource.com/964244
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543819}

ash/shelf/shelf.cc

@@ -76,6 +76,7 @@ void Shelf::CreateShelfWidget(aura::Window* root) {
   aura::Window* shelf_container =
       root->GetChildById(kShellWindowId_ShelfContainer);
   shelf_widget_.reset(new ShelfWidget(shelf_container, this));
+  shelf_widget_->Initialize();
 
   DCHECK(!shelf_layout_manager_);
   shelf_layout_manager_ = shelf_widget_->shelf_layout_manager();

ash/shelf/shelf_widget.cc

@@ -212,9 +212,6 @@ ShelfWidget::ShelfWidget(aura::Window* shelf_container, Shelf* shelf)
   // Calls back into |this| and depends on |shelf_view_|.
   background_animator_.AddObserver(this);
   background_animator_.AddObserver(delegate_view_);
-
-  // Sets initial session state to make sure the UI is properly shown.
-  OnSessionStateChanged(Shell::Get()->session_controller()->GetSessionState());
 }
 
 ShelfWidget::~ShelfWidget() {
@@ -222,6 +219,11 @@ ShelfWidget::~ShelfWidget() {
   DCHECK(!status_area_widget_);
 }
 
+void ShelfWidget::Initialize() {
+  // Sets initial session state to make sure the UI is properly shown.
+  OnSessionStateChanged(Shell::Get()->session_controller()->GetSessionState());
+}
+
 void ShelfWidget::Shutdown() {
   // Shutting down the status area widget may cause some widgets (e.g. bubbles)
   // to close, so uninstall the ShelfLayoutManager event filters first. Don't

ash/shelf/shelf_widget.h

@@ -43,6 +43,12 @@ class ASH_EXPORT ShelfWidget : public views::Widget,
   ShelfWidget(aura::Window* shelf_container, Shelf* shelf);
   ~ShelfWidget() override;
 
+  // Sets the initial session state and show the UI. Not part of the constructor
+  // because showing the UI triggers the accessibility checks in browser_tests,
+  // which will crash unless the constructor returns, allowing the caller
+  // to store the constructed widget.
+  void Initialize();
+
   // Clean up prior to deletion.
   void Shutdown();