Make ExtensionsToolbarButton's button controller a MenuButtonController.

This is needed to have access to MenuButtonController::PressedLock and ToolbarActionView assumes that this will exist for a popup's reference button.

Bug: 995448
Change-Id: I4855d4e30c38d530c6e8eadf7047ddc518258977
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1919660Reviewed-by: Dana Fried <dfried@chromium.org>
Commit-Queue: Dana Fried <dfried@chromium.org>
Cr-Commit-Position: refs/heads/master@{#715969}

chrome/browser/ui/views/extensions/extensions_toolbar_button.cc

@@ -23,6 +23,13 @@ ExtensionsToolbarButton::ExtensionsToolbarButton(
     : ToolbarButton(this),
       browser_(browser),
       extensions_container_(extensions_container) {
+  std::unique_ptr<views::MenuButtonController> menu_button_controller =
+      std::make_unique<views::MenuButtonController>(
+          this, this,
+          std::make_unique<views::Button::DefaultButtonControllerDelegate>(
+              this));
+  menu_button_controller_ = menu_button_controller.get();
+  SetButtonController(std::move(menu_button_controller));
   SetTooltipText(l10n_util::GetStringUTF16(IDS_TOOLTIP_EXTENSIONS_BUTTON));
   button_controller()->set_notify_action(
       views::ButtonController::NotifyAction::kOnPress);

chrome/browser/ui/views/extensions/extensions_toolbar_button.h

@@ -10,6 +10,10 @@
 class Browser;
 class ExtensionsToolbarContainer;
 
+namespace views {
+class MenuButtonController;
+}  // namespace views
+
 // Button in the toolbar that provides access to the corresponding extensions
 // menu.
 class ExtensionsToolbarButton : public ToolbarButton,
@@ -25,6 +29,7 @@ class ExtensionsToolbarButton : public ToolbarButton,
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
   Browser* const browser_;
+  views::MenuButtonController* menu_button_controller_;
   ExtensionsToolbarContainer* const extensions_container_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionsToolbarButton);