[Android] Add UMA for pull-to-refresh activation

content/browser/android/overscroll_controller_android.cc

Index: content/browser/android/overscroll_controller_android.cc
diff --git a/content/browser/android/overscroll_controller_android.cc b/content/browser/android/overscroll_controller_android.cc
index 0f161d8fdd9d4395df71efb64c03ae00cb29a032..c6c41531d4e977dd5e04cf4759df49b0c14babca 100644
--- a/content/browser/android/overscroll_controller_android.cc
+++ b/content/browser/android/overscroll_controller_android.cc
@@ -13,6 +13,7 @@
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/common/input/did_overscroll_params.h"
 #include "content/public/browser/navigation_controller.h"
+#include "content/public/browser/user_metrics.h"
 #include "content/public/common/content_switches.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "ui/android/resources/resource_manager.h"
@@ -277,6 +278,7 @@ void OverscrollControllerAndroid::TriggerRefresh() {
     return;
 
   triggered_refresh_active_ = true;
+  RecordAction(base::UserMetricsAction("MobilePullGestureReload"));
   web_contents()->GetController().Reload(true);
 }