binderwrapper: Resolve ambiguous base::Closure reference

Disambiguate between base and android::base namespaces.  This matters
when headers from libbase are indirectly included.

Bug: 27804373
Test: Compiles in that referenced situation.

Change-Id: Icb26595bb0013733aa8c03971c9f4a950c8b2ab1
diff --git a/libbinderwrapper/real_binder_wrapper.h b/libbinderwrapper/real_binder_wrapper.h
index ea08371..1675432 100644
--- a/libbinderwrapper/real_binder_wrapper.h
+++ b/libbinderwrapper/real_binder_wrapper.h
@@ -36,7 +36,7 @@
                        const sp<IBinder>& binder) override;
   sp<BBinder> CreateLocalBinder() override;
   bool RegisterForDeathNotifications(const sp<IBinder>& binder,
-                                     const base::Closure& callback) override;
+                                     const ::base::Closure& callback) override;
   bool UnregisterForDeathNotifications(const sp<IBinder>& binder) override;
   uid_t GetCallingUid() override;
   pid_t GetCallingPid() override;