Fixes possible use after free in SessionService

chrome/browser/sessions/session_service_test_helper.h

Index: chrome/browser/sessions/session_service_test_helper.h
diff --git a/chrome/browser/sessions/session_service_test_helper.h b/chrome/browser/sessions/session_service_test_helper.h
index 7f176c727bec3dc074fe646c10b17453f316935f..8daadd8e5773ba06b3d276246816403989d455b7 100644
--- a/chrome/browser/sessions/session_service_test_helper.h
+++ b/chrome/browser/sessions/session_service_test_helper.h
@@ -10,6 +10,7 @@
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/message_loop/message_loop.h"
 #include "components/sessions/session_id.h"
 
 class SessionBackend;
@@ -18,6 +19,10 @@ class SessionService;
 struct SessionTab;
 struct SessionWindow;
 
+namespace base {
+class RunLoop;
+}
+
 namespace sessions {
 class SerializedNavigationEntry;
 }
@@ -76,6 +81,9 @@ class SessionServiceTestHelper {
 
   SessionBackend* backend();
 
+  void RunTaskOnBackendThread(const tracked_objects::Location& from_here,
+                              const base::Closure& task);
+
  private:
   scoped_ptr<SessionService> service_;