Add UMA stats for SharedWorker in SharedWorkerHost.

content/browser/shared_worker/shared_worker_host.h

Index: content/browser/shared_worker/shared_worker_host.h
diff --git a/content/browser/shared_worker/shared_worker_host.h b/content/browser/shared_worker/shared_worker_host.h
index 4292d74820e279337b2075c488a9974572ba9ece..f46e3b2a5b464b9250d05ff7e24d4f368531c866 100644
--- a/content/browser/shared_worker/shared_worker_host.h
+++ b/content/browser/shared_worker/shared_worker_host.h
@@ -9,6 +9,7 @@
 
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string16.h"
+#include "base/time/time.h"
 #include "content/browser/shared_worker/shared_worker_message_filter.h"
 
 class GURL;
@@ -88,6 +89,7 @@ class SharedWorkerHost {
   scoped_ptr<SharedWorkerInstance> instance_;
   SharedWorkerMessageFilter* container_render_filter_;
   int worker_route_id_;
+  const base::TimeTicks creation_time_;
   DISALLOW_COPY_AND_ASSIGN(SharedWorkerHost);
 };
 }  // namespace content