Make MenuItemView default constructible

Make MenuItemView's delegate an optional argument in its constructor so
it can be default constructed. Its delegate can always be set thru the
existing set_delegate() function. Also need to add a few more checks for
the return delegate pointer.

Bug: 1108460
Change-Id: Ie90709271c971cadccf3e13166df0c240d73dfca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2321526Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Wei Li <weili@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792836}

ui/views/controls/menu/menu_item_view.cc

@@ -174,7 +174,9 @@ base::string16 MenuItemView::GetTooltipText(const gfx::Point& p) const {
   }
 
   const MenuDelegate* delegate = GetDelegate();
-  CHECK(delegate);
+  if (!delegate)
+    return base::string16();
+
   gfx::Point location(p);
   ConvertPointToScreen(this, &location);
   return delegate->GetTooltipText(command_, location);
@@ -215,7 +217,8 @@ void MenuItemView::GetAccessibleNodeData(ui::AXNodeData* node_data) {
       break;
     case Type::kCheckbox:
     case Type::kRadio: {
-      const bool is_checked = GetDelegate()->IsItemChecked(GetCommand());
+      const bool is_checked =
+          GetDelegate() && GetDelegate()->IsItemChecked(GetCommand());
       node_data->SetCheckedState(is_checked ? ax::mojom::CheckedState::kTrue
                                             : ax::mojom::CheckedState::kFalse);
     } break;
@@ -816,7 +819,7 @@ void MenuItemView::Init(MenuItemView* parent,
   if (type_ == Type::kCheckbox || type_ == Type::kRadio) {
     radio_check_image_view_ = AddChildView(std::make_unique<ImageView>());
     bool show_check_radio_icon =
-        type_ == Type::kRadio || (type_ == Type::kCheckbox &&
+        type_ == Type::kRadio || (type_ == Type::kCheckbox && GetDelegate() &&
                                   GetDelegate()->IsItemChecked(GetCommand()));
     radio_check_image_view_->SetVisible(show_check_radio_icon);
     radio_check_image_view_->set_can_process_events_within_subtree(false);
@@ -943,7 +946,6 @@ void MenuItemView::PaintButton(gfx::Canvas* canvas, PaintButtonMode mode) {
   if (forced_visual_selection_.has_value())
     render_selection = *forced_visual_selection_;
 
-  MenuDelegate* delegate = GetDelegate();
   // Render the background. As MenuScrollViewContainer draws the background, we
   // only need the background when we want it to look different, as when we're
   // selected.
@@ -966,10 +968,12 @@ void MenuItemView::PaintButton(gfx::Canvas* canvas, PaintButtonMode mode) {
   top_margin += (available_height - total_text_height) / 2;
 
   // Render the check.
-  if (type_ == Type::kCheckbox && delegate->IsItemChecked(GetCommand())) {
+  MenuDelegate* delegate = GetDelegate();
+  if (type_ == Type::kCheckbox && delegate &&
+      delegate->IsItemChecked(GetCommand())) {
     radio_check_image_view_->SetImage(GetMenuCheckImage(icon_color));
   } else if (type_ == Type::kRadio) {
-    const bool toggled = delegate->IsItemChecked(GetCommand());
+    const bool toggled = delegate && delegate->IsItemChecked(GetCommand());
     const gfx::VectorIcon& radio_icon =
         toggled ? kMenuRadioSelectedIcon : kMenuRadioEmptyIcon;
     const SkColor radio_icon_color = GetNativeTheme()->GetSystemColor(

ui/views/controls/menu/menu_item_view.h

@@ -117,7 +117,7 @@ class VIEWS_EXPORT MenuItemView : public View {
 
   // Constructor for use with the top level menu item. This menu is never
   // shown to the user, rather its use as the parent for all menu items.
-  explicit MenuItemView(MenuDelegate* delegate);
+  explicit MenuItemView(MenuDelegate* delegate = nullptr);
 
   // Overridden from View:
   base::string16 GetTooltipText(const gfx::Point& p) const override;

ui/views/controls/menu/submenu_view_unittest.cc

@@ -11,7 +11,7 @@
 namespace views {
 
 TEST(SubmenuViewTest, GetLastItem) {
-  MenuItemView* parent = new MenuItemView(nullptr);
+  MenuItemView* parent = new MenuItemView();
   MenuRunner menu_runner(parent, 0);
 
   SubmenuView* submenu = parent->CreateSubmenu();
@@ -20,14 +20,14 @@ TEST(SubmenuViewTest, GetLastItem) {
   submenu->AddChildView(new View());
   EXPECT_EQ(nullptr, submenu->GetLastItem());
 
-  MenuItemView* first = new MenuItemView(nullptr);
+  MenuItemView* first = new MenuItemView();
   submenu->AddChildView(first);
   EXPECT_EQ(first, submenu->GetLastItem());
 
   submenu->AddChildView(new View());
   EXPECT_EQ(first, submenu->GetLastItem());
 
-  MenuItemView* second = new MenuItemView(nullptr);
+  MenuItemView* second = new MenuItemView();
   submenu->AddChildView(second);
   EXPECT_EQ(second, submenu->GetLastItem());
 }

ui/views/controls/menu/test_menu_item_view.cc

@@ -6,7 +6,7 @@
 
 namespace views {
 
-TestMenuItemView::TestMenuItemView() : MenuItemView(nullptr) {}
+TestMenuItemView::TestMenuItemView() = default;
 
 TestMenuItemView::TestMenuItemView(MenuDelegate* delegate)
     : MenuItemView(delegate) {}