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

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index 1f77258d8df738cac0a5efbef2df7b78dd3e1711..31b7bffccd1c7cc090626b862b63063b7301312e 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -20,6 +20,7 @@
 #include "base/memory/ptr_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
+#include "base/metrics/user_metrics.h"
 #include "base/pending_task.h"
 #include "base/power_monitor/power_monitor.h"
 #include "base/power_monitor/power_monitor_device_source.h"
@@ -590,6 +591,11 @@ void BrowserMainLoop::PostMainMessageLoopStart() {
             base::ThreadTaskRunnerHandle::Get()));
   }
 
+  {

[Alexei Svitkine (slow), 2016/04/22 14:30:13]

Nit: why the {}'s?

+    base::SetRecordActionTaskRunner(
+        BrowserThread::GetMessageLoopProxyForThread(BrowserThread::UI));
+  }
+
 #if defined(OS_WIN)
   if (base::win::GetVersion() >= base::win::VERSION_WIN8)
     screen_orientation_delegate_.reset(new ScreenOrientationDelegateWin());