Move views::Accelerator to ui in order to use it from aura code.

views/bubble/bubble_delegate.cc

Index: views/bubble/bubble_delegate.cc
diff --git a/views/bubble/bubble_delegate.cc b/views/bubble/bubble_delegate.cc
index c5b27eecd82d429d535d32df7fd477cdfa31780d..a117a08d3b2eadc73bd3424566413b80c4740d86 100644
--- a/views/bubble/bubble_delegate.cc
+++ b/views/bubble/bubble_delegate.cc
@@ -197,7 +197,8 @@ void BubbleDelegateView::ResetFade() {
   GetWidget()->SetOpacity(original_opacity_);
 }
 
-bool BubbleDelegateView::AcceleratorPressed(const Accelerator& accelerator) {
+bool BubbleDelegateView::AcceleratorPressed(
+    const ui::Accelerator& accelerator) {
   if (!close_on_esc() || accelerator.key_code() != ui::VKEY_ESCAPE)
     return false;
   if (fade_animation_.get())