Cast: added missing include in simple_event_subscriber.h.

Some build envs don't understand OVERRIDE without that header.

Review URL: https://codereview.chromium.org/165693003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251463 0039d316-1c4b-4281-b951-d872f2087c98

media/cast/logging/simple_event_subscriber.h

@@ -7,6 +7,7 @@
 
 #include <vector>
 
+#include "base/compiler_specific.h"
 #include "base/threading/thread_checker.h"
 #include "media/cast/logging/raw_event_subscriber.h"