Adds tracing to investigate infinite calls to SetAutoHideBehavior

ash/common/shelf/wm_shelf.cc

 // 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.
 
 #include "ash/common/shelf/wm_shelf.h"
 
 #include "ash/common/shelf/shelf_controller.h"
 #include "ash/common/shelf/shelf_delegate.h"
 #include "ash/common/shelf/shelf_item_delegate.h"
 #include "ash/common/shelf/shelf_layout_manager.h"
@@ skipping 148 matching lines @@
   return bottom;
 }
 
 int WmShelf::PrimaryAxisValue(int horizontal, int vertical) const {
   return IsHorizontalAlignment() ? horizontal : vertical;
 }
 
 void WmShelf::SetAutoHideBehavior(ShelfAutoHideBehavior auto_hide_behavior) {
   DCHECK(shelf_layout_manager_);
 
+  // Force a stack dump when this method is invoked too frequently.
+  // This block is here temporary to help investigate http://crbug.com/665093 .
+  constexpr int kAutoHideRepeatInterval = 10000;
+  constexpr int kMaxAutoHideChangesIn10Seconds = 100;
+  if ((base::TimeTicks::Now() - time_last_auto_hide_change_).InMilliseconds() <
+      kAutoHideRepeatInterval) {
+    if (++count_auto_hide_changes_ > kMaxAutoHideChangesIn10Seconds)
+      CHECK(false);
+  } else {
+    count_auto_hide_changes_ = 0;
+  }
+  time_last_auto_hide_change_ = base::TimeTicks::Now();
+
   if (auto_hide_behavior_ == auto_hide_behavior)
     return;
 
   auto_hide_behavior_ = auto_hide_behavior;
   WmShell::Get()->shelf_controller()->NotifyShelfAutoHideBehaviorChanged(this);
   WmShell::Get()->NotifyShelfAutoHideBehaviorChanged(
       GetWindow()->GetRootWindow());
 }
 
 ShelfAutoHideState WmShelf::GetAutoHideState() const {
@@ skipping 147 matching lines @@
 
 void WmShelf::OnBackgroundUpdated(ShelfBackgroundType background_type,
                                   BackgroundAnimatorChangeType change_type) {
   if (background_type == GetBackgroundType())
     return;
   for (auto& observer : observers_)
     observer.OnBackgroundTypeChanged(background_type, change_type);
 }
 
 }  // namespace ash