Adds tracing to investigate infinite calls to SetAutoHideBehavior

ash/common/shelf/wm_shelf.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ASH_COMMON_SHELF_WM_SHELF_H_
 #define ASH_COMMON_SHELF_WM_SHELF_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
 #include "ash/common/shelf/shelf_layout_manager_observer.h"
 #include "ash/public/cpp/shelf_types.h"
 #include "base/observer_list.h"
+#include "base/time/time.h"
 
 namespace gfx {
 class Rect;
 }
 
 namespace ui {
 class GestureEvent;
 }
 
 namespace ash {
@@ skipping 145 matching lines @@
 
   ShelfAlignment alignment_ = SHELF_ALIGNMENT_BOTTOM_LOCKED;
 
   // Sets shelf alignment to bottom during login and screen lock.
   std::unique_ptr<ShelfLockingManager> shelf_locking_manager_;
 
   ShelfAutoHideBehavior auto_hide_behavior_ = SHELF_AUTO_HIDE_BEHAVIOR_NEVER;
 
   base::ObserverList<WmShelfObserver> observers_;
 
+  // Temporary. Used to investigate http://crbug.com/665093 .
+  base::TimeTicks time_last_auto_hide_change_;
+  int count_auto_hide_changes_ = 0;
+
   DISALLOW_COPY_AND_ASSIGN(WmShelf);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SHELF_WM_SHELF_H_