Clean up event flags a bit:

components/exo/pointer.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/exo/pointer.h"
 
 #include "ash/shell.h"
 #include "components/exo/pointer_delegate.h"
 #include "components/exo/surface.h"
 #include "ui/aura/window.h"
@@ skipping 26 matching lines @@
   // generate enter and leave events.
   if (target != focus_) {
     // First generate a leave event if we currently have a target in focus.
     if (focus_) {
       delegate_->OnPointerLeave(focus_);
       focus_->RemoveSurfaceObserver(this);
       focus_ = nullptr;
     }
     // Second generate an enter event if focus moved to a new target.
     if (target) {
-      int button_flags =
-          event->flags() &
-          (ui::EF_LEFT_MOUSE_BUTTON | ui::EF_MIDDLE_MOUSE_BUTTON |
-           ui::EF_RIGHT_MOUSE_BUTTON | ui::EF_BACK_MOUSE_BUTTON |
-           ui::EF_FORWARD_MOUSE_BUTTON);
-      delegate_->OnPointerEnter(target, event->location(), button_flags);
+      delegate_->OnPointerEnter(target, event->location(),
+                                event->button_flags());
       location_ = event->location();
       focus_ = target;
       focus_->AddSurfaceObserver(this);
     }
   }
   switch (event->type()) {
     case ui::ET_MOUSE_PRESSED:
     case ui::ET_MOUSE_RELEASED:
       if (focus_) {
         delegate_->OnPointerButton(event->time_stamp(),
@@ skipping 44 matching lines @@
 Surface* Pointer::GetEffectiveTargetForEvent(ui::Event* event) const {
   Surface* target =
       Surface::AsSurface(static_cast<aura::Window*>(event->target()));
   if (!target)
     return nullptr;
 
   return delegate_->CanAcceptPointerEventsForSurface(target) ? target : nullptr;
 }
 
 }  // namespace exo