Replace views::MouseEvent with ui::MouseEvent

ash/system/tray/tray_bubble_view.cc

Index: ash/system/tray/tray_bubble_view.cc
===================================================================
--- ash/system/tray/tray_bubble_view.cc	(revision 151406)
+++ ash/system/tray/tray_bubble_view.cc	(working copy)
@@ -389,12 +389,12 @@
   return gfx::Size(params_.bubble_width, height);
 }
 
-void TrayBubbleView::OnMouseEntered(const views::MouseEvent& event) {
+void TrayBubbleView::OnMouseEntered(const ui::MouseEvent& event) {
   if (host_)
     host_->OnMouseEnteredView();
 }
 
-void TrayBubbleView::OnMouseExited(const views::MouseEvent& event) {
+void TrayBubbleView::OnMouseExited(const ui::MouseEvent& event) {
   if (host_)
     host_->OnMouseExitedView();
 }