Added the "DISALLOW_COPY_AND_ASSIGN(Timer);" for Timer class in gin/module/timer.h.

BUG=

Review URL: https://codereview.chromium.org/587713002

Cr-Commit-Position: refs/heads/master@{#295948}

gin/modules/timer.h

@@ -42,6 +42,7 @@ class GIN_EXPORT Timer : public Wrappable<Timer> {
   base::WeakPtr<gin::Runner> runner_;
   base::WeakPtrFactory<Timer> weak_factory_;
 
+  DISALLOW_COPY_AND_ASSIGN(Timer);
 };