Move the thread hop for UMA user actions from content:: to base::.

base/test/user_action_tester.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_TEST_USER_ACTION_TESTER_H_
 #define BASE_TEST_USER_ACTION_TESTER_H_
 
 #include <map>
 #include <string>
 
@@ skipping 18 matching lines @@
 
  private:
   typedef std::map<std::string, int> UserActionCountMap;
 
   // The callback that is notified when a user actions occurs.
   void OnUserAction(const std::string& user_action);
 
   // A map that tracks the number of times a user action has occurred.
   UserActionCountMap count_map_;
 
+  // A test task runner used by user metrics.
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
   // The callback that is added to the global action callback list.
   base::ActionCallback action_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(UserActionTester);
 };
 
 }  // namespace base
 
 #endif  // BASE_TEST_USER_ACTION_TESTER_H_