Suppress race detected by Tsan in talk_base::Event.

BUG=116421
TBR=ronghuawu@chromium.org

Review URL: https://chromiumcodereview.appspot.com/9564019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@124463 0039d316-1c4b-4281-b951-d872f2087c98

tools/valgrind/tsan/suppressions.txt

@@ -851,4 +851,8 @@
   fun:AudioRendererHost::OnCreated
   fun:media::AudioOutputController::DoCreate
 }
-
+{
+  bug_116421
+  ThreadSanitizer:Race
+  fun:talk_base::Event::EnsureInitialized
+}