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

base/metrics/user_metrics.h

 // Copyright 2014 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_METRICS_USER_METRICS_H_
 #define BASE_METRICS_USER_METRICS_H_
 
 #include <string>
 
 #include "base/base_export.h"
 #include "base/callback.h"
 #include "base/metrics/user_metrics_action.h"
+#include "base/single_thread_task_runner.h"
 
 namespace base {
 
 // This module provides some helper functions for logging actions tracked by
 // the user metrics system.
 
 // Record that the user performed an action.
 // This method *must* be called from the main thread.
 //
 // "Action" here means a user-generated event:
@@ skipping 25 matching lines @@
 // tools/metrics/actions/extract_actions.py.
 BASE_EXPORT void RecordComputedAction(const std::string& action);
 
 // Called with the action string.
 typedef base::Callback<void(const std::string&)> ActionCallback;
 
 // Add/remove action callbacks (see above).
 BASE_EXPORT void AddActionCallback(const ActionCallback& callback);
 BASE_EXPORT void RemoveActionCallback(const ActionCallback& callback);
 
+// Set the task runner on which to do the thread hopping.

[Ilya Sherman, 2016/04/06 02:36:29]

nit: Perhaps "Set the task runner on which to record actions." or something like
it?

[beaudoin, 2016/04/06 15:06:13]

Done.

+BASE_EXPORT void SetRecordActionTaskRunner(
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner);
+
+

[Ilya Sherman, 2016/04/06 02:36:29]

nit: Spurious newline

[beaudoin, 2016/04/06 15:06:13]

Done.

 }  // namespace base
 
 #endif  // BASE_METRICS_USER_METRICS_H_