The following test fails in mash_unittests but succeeds in ash_unitests (and
ash_unittests --mus).

In the original test, the 'ABC1' events are not delivered to |content|, but
VKEY_RETURN is.


    // Fails in mash_unittests, succeeds in ash_unittests.
    using Fixture = ash::test::AshTestBase;
    TEST_F(Fixture, MashEventRouterBug) {
      auto* content = new views::Textfield();
    
      views::Widget::InitParams params(
          views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
      params.context = CurrentContext();
      params.bounds = gfx::Rect(0, 0, 800, 800);
      auto* widget = new views::Widget();
      widget->Init(params);
      widget->SetContentsView(content);
      widget->Show();
    
      content->RequestFocus();
      EXPECT_EQ(content->GetFocusManager()->GetFocusedView(),
                content);
    
      ui::test::EventGenerator& generator = GetEventGenerator();
      generator.PressKey(ui::KeyboardCode::VKEY_A, 0);
      generator.PressKey(ui::KeyboardCode::VKEY_B, 0);
      generator.PressKey(ui::KeyboardCode::VKEY_C, 0);
      generator.PressKey(ui::KeyboardCode::VKEY_1, 0);
      generator.PressKey(ui::KeyboardCode::VKEY_RETURN, 0);
    
      EXPECT_EQ(base::ASCIIToUTF16("abc1"), content->text());
    }