Eliminate hacks needed to work around a limitation of base::Bind()

dbus/object_proxy.h

Index: dbus/object_proxy.h
diff --git a/dbus/object_proxy.h b/dbus/object_proxy.h
index ffd59c297232f392a91ed482a56697a6d3d6f330..a950e941188633671c0897f71a1d7027ee86d137 100644
--- a/dbus/object_proxy.h
+++ b/dbus/object_proxy.h
@@ -129,7 +129,7 @@ class ObjectProxy : public base::RefCountedThreadSafe<ObjectProxy> {
   // Starts the async method call. This is a helper function to implement
   // CallMethod().
   void StartAsyncMethodCall(int timeout_ms,
-                            void* request_message,
+                            DBusMessage* request_message,
                             ResponseCallback response_callback,
                             base::TimeTicks start_time);
 
@@ -141,7 +141,7 @@ class ObjectProxy : public base::RefCountedThreadSafe<ObjectProxy> {
   // Runs the response callback with the given response object.
   void RunResponseCallback(ResponseCallback response_callback,
                            base::TimeTicks start_time,
-                           void* response_message);
+                           DBusMessage* response_message);
 
   // Redirects the function call to OnPendingCallIsComplete().
   static void OnPendingCallIsCompleteThunk(DBusPendingCall* pending_call,