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

base/test/user_action_tester.cc

Index: base/test/user_action_tester.cc
diff --git a/base/test/user_action_tester.cc b/base/test/user_action_tester.cc
index 3fdab121b4756f23be40a5b903a8825f69b01f12..6c3de39c17a4a21777552392fc2589ed298b53b3 100644
--- a/base/test/user_action_tester.cc
+++ b/base/test/user_action_tester.cc
@@ -6,12 +6,15 @@
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
+#include "base/test/test_simple_task_runner.h"
 
 namespace base {
 
 UserActionTester::UserActionTester()
-    : action_callback_(
+    : task_runner_(new base::TestSimpleTaskRunner),
+      action_callback_(
           base::Bind(&UserActionTester::OnUserAction, base::Unretained(this))) {
+  base::SetRecordActionTaskRunner(task_runner_);
   base::AddActionCallback(action_callback_);
 }