Explicitly coerce PostDispatchAction to uint32_t in DispatchEvent()

ui/events/platform/platform_event_dispatcher.h

 // 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.
 
 #ifndef UI_EVENTS_PLATFORM_PLATFORM_EVENT_DISPATCHER_H_
 #define UI_EVENTS_PLATFORM_PLATFORM_EVENT_DISPATCHER_H_
 
 #include "base/basictypes.h"
 #include "ui/events/events_export.h"
 #include "ui/events/platform/platform_event_types.h"
 
 namespace ui {
 
 // See documentation for |PlatformEventDispatcher::DispatchEvent()| for
 // explanation of the meaning of the flags.
-enum PostDispatchAction {
-  POST_DISPATCH_NONE = 0x0,

[sky, 2014/10/20 20:58:37]

I prefer the enum. It's more typical of how we do these sort of things in
Chrome.

-  POST_DISPATCH_PERFORM_DEFAULT = 0x1,
-  POST_DISPATCH_STOP_PROPAGATION = 0x2,
-};
+typedef uint32_t PostDispatchAction;
+const PostDispatchAction kPostDispatchNone = 0;
+const PostDispatchAction kPostDispatchPerformDefault = 1 << 0;
+const PostDispatchAction kPostDispatchStopPropagation = 1 << 1;
 
 // PlatformEventDispatcher receives events from a PlatformEventSource and
 // dispatches them.
 class EVENTS_EXPORT PlatformEventDispatcher {
  public:
   // Returns whether this dispatcher wants to dispatch |event|.
   virtual bool CanDispatchEvent(const PlatformEvent& event) = 0;
 
   // Dispatches |event|. If this is not the default dispatcher, then the
   // dispatcher can request that the default dispatcher gets a chance to
-  // dispatch the event by setting POST_DISPATCH_PERFORM_DEFAULT to the return
+  // dispatch the event by setting kPostDispatchPerformDefault to the return
   // value. If the dispatcher has processed the event, and no other dispatcher
   // should be allowed to dispatch the event, then the dispatcher should set
-  // POST_DISPATCH_STOP_PROPAGATION flag on the return value.
-  virtual uint32_t DispatchEvent(const PlatformEvent& event) = 0;
+  // kPostDispatchStopPropagation flag on the return value.
+  virtual PostDispatchAction DispatchEvent(const PlatformEvent& event) = 0;
 
  protected:
   virtual ~PlatformEventDispatcher() {}
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_PLATFORM_PLATFORM_EVENT_DISPATCHER_H_