Fix button-pressed handling in ImeDetailedView

ImeDetailedView::HandleButtonPressed() now calls up to
its superclass ImeListView::HandleButtonPressed() in
order to handle clicks on the VK toggle button.

BUG=657146
TEST=ash_unittests

Review-Url: https://codereview.chromium.org/2513713002
Cr-Commit-Position: refs/heads/master@{#433076}

ash/common/system/chromeos/ime_menu/ime_list_view.cc

@@ -399,9 +399,10 @@ void ImeListView::HandleViewClicked(views::View* view) {
 
 void ImeListView::HandleButtonPressed(views::Button* sender,
                                       const ui::Event& event) {
-  DCHECK(material_keyboard_status_view_);
-  DCHECK_EQ(sender, material_keyboard_status_view_->toggle());
-  WmShell::Get()->ToggleIgnoreExternalKeyboard();
+  if (material_keyboard_status_view_ &&
+      sender == material_keyboard_status_view_->toggle()) {
+    WmShell::Get()->ToggleIgnoreExternalKeyboard();
+  }
 }
 
 }  // namespace ash

ash/common/system/ime/tray_ime_chromeos.cc

@@ -153,6 +153,7 @@ class IMEDetailedView : public ImeListView {
 
   void HandleButtonPressed(views::Button* sender,
                            const ui::Event& event) override {
+    ImeListView::HandleButtonPressed(sender, event);
     if (sender == settings_button_)
       ShowSettings();
   }