Clean up event flags a bit:

ui/aura/window_event_dispatcher.cc

 // Copyright 2014 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 "ui/aura/window_event_dispatcher.h"
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 773 matching lines @@
       event->SetHandled();
       return DispatchDetails();
     } else {
       // We may have a held event for a period between the time move_hold_count_
       // fell to 0 and the DispatchHeldEvents executes. Since we're going to
       // dispatch the new event directly below, we can reset the old one.
       held_move_event_.reset();
     }
   }
 
-  const int kMouseButtonFlagMask = 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;
   switch (event->type()) {
     case ui::ET_MOUSE_EXITED:
       if (!target || target == window()) {
         DispatchDetails details =
             DispatchMouseEnterOrExit(target, *event, ui::ET_MOUSE_EXITED);
         if (details.dispatcher_destroyed) {
           event->SetHandled();
           return details;
         }
         mouse_moved_handler_ = NULL;
@@ skipping 40 matching lines @@
         }
       }
       break;
     case ui::ET_MOUSE_PRESSED:
       // Don't set the mouse pressed handler for non client mouse down events.
       // These are only sent by Windows and are not always followed with non
       // client mouse up events which causes subsequent mouse events to be
       // sent to the wrong target.
       if (!(event->flags() & ui::EF_IS_NON_CLIENT) && !mouse_pressed_handler_)
         mouse_pressed_handler_ = target;
-      Env::GetInstance()->set_mouse_button_flags(
-          event->flags() & kMouseButtonFlagMask);
+      Env::GetInstance()->set_mouse_button_flags(event->button_flags());
       break;
     case ui::ET_MOUSE_RELEASED:
       mouse_pressed_handler_ = NULL;
-      Env::GetInstance()->set_mouse_button_flags(event->flags() &
-          kMouseButtonFlagMask & ~event->changed_button_flags());
+      Env::GetInstance()->set_mouse_button_flags(
+          event->button_flags() & ~event->changed_button_flags());
       break;
     default:
       break;
   }
 
   return PreDispatchLocatedEvent(target, event);
 }
 
 DispatchDetails WindowEventDispatcher::PreDispatchTouchEvent(
     Window* target,
@@ skipping 38 matching lines @@
   }
 
   // This flag is set depending on the gestures recognized in the call above,
   // and needs to propagate with the forwarded event.
   event->set_may_cause_scrolling(orig_event.may_cause_scrolling());
 
   return PreDispatchLocatedEvent(target, event);
 }
 
 }  // namespace aura