Remove unnecessary mocking of TickClock for events

ui/chromeos/touch_exploration_controller.h

Index: ui/chromeos/touch_exploration_controller.h
diff --git a/ui/chromeos/touch_exploration_controller.h b/ui/chromeos/touch_exploration_controller.h
index 270a86000511dfdc73177928ef05db63d7e1fd39..da042d11e3fa135ea2078c4d86b8b7b259bc9ce3 100644
--- a/ui/chromeos/touch_exploration_controller.h
+++ b/ui/chromeos/touch_exploration_controller.h
@@ -6,7 +6,6 @@
 #define UI_CHROMEOS_TOUCH_EXPLORATION_CONTROLLER_H_
 
 #include "base/macros.h"
-#include "base/time/tick_clock.h"
 #include "base/timer/timer.h"
 #include "base/values.h"
 #include "ui/accessibility/ax_enums.h"
@@ -501,10 +500,6 @@ class UI_CHROMEOS_EXPORT TouchExplorationController
   // This toggles whether VLOGS are turned on or not.
   bool VLOG_on_;
 
-  // When touch_exploration_controller gets time relative to real time during
-  // testing, this clock is set to the simulated clock and used.
-  base::TickClock* tick_clock_;
-
   DISALLOW_COPY_AND_ASSIGN(TouchExplorationController);
 };