Adding UMA logging to touch text selection

ui/touch_selection/touch_selection_controller.h

Index: ui/touch_selection/touch_selection_controller.h
diff --git a/ui/touch_selection/touch_selection_controller.h b/ui/touch_selection/touch_selection_controller.h
index 2bcefbd20542c1a12477ccb93ed6eec25fc7a8ea..da1d9648982d9cd00dc4eec53835f228e679c67c 100644
--- a/ui/touch_selection/touch_selection_controller.h
+++ b/ui/touch_selection/touch_selection_controller.h
@@ -115,6 +115,8 @@ class UI_TOUCH_SELECTION_EXPORT TouchSelectionController
   bool GetEndVisible() const;
   TouchHandle::AnimationStyle GetAnimationStyle(bool was_active) const;
 
+  void LogSelectionEnd();
+
   TouchSelectionControllerClient* const client_;
   const base::TimeDelta tap_timeout_;
   const float tap_slop_;
@@ -140,6 +142,8 @@ class UI_TOUCH_SELECTION_EXPORT TouchSelectionController
 
   bool temporarily_hidden_;
 
+  base::Time selection_start_time_;
+
   DISALLOW_COPY_AND_ASSIGN(TouchSelectionController);
 };