Make sure WindowObservers are removed from window before destruction

ui/views/corewm/tooltip_controller.cc

 // Copyright (c) 2012 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 "ui/views/corewm/tooltip_controller.h"
 
 #include <vector>
 
 #include "base/strings/string_util.h"
 #include "base/time/time.h"
@@ skipping 209 matching lines @@
 }
 
 void TooltipController::OnCancelMode(ui::CancelModeEvent* event) {
   tooltip_->Hide();
 }
 
 void TooltipController::OnWindowDestroyed(aura::Window* window) {
   if (tooltip_window_ == window) {
     tooltip_->Hide();
     tooltip_shown_timeout_map_.erase(tooltip_window_);
-    tooltip_window_->RemoveObserver(this);
     tooltip_window_ = NULL;
   }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // TooltipController private:
 
 void TooltipController::TooltipTimerFired() {
   UpdateIfRequired();
 }
@@ skipping 88 matching lines @@
 int TooltipController::GetTooltipShownTimeout() {
   std::map<aura::Window*, int>::const_iterator it =
       tooltip_shown_timeout_map_.find(tooltip_window_);
   if (it == tooltip_shown_timeout_map_.end())
     return kDefaultTooltipShownTimeoutMs;
   return it->second;
 }
 
 }  // namespace corewm
 }  // namespace views