Fix null pointer dereference in FocusManager::ViewRemoved.

ui/views/focus/focus_manager.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/focus/focus_manager.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/auto_reset.h"
@@ skipping 499 matching lines @@
 // static
 bool FocusManager::IsTabTraversalKeyEvent(const ui::KeyEvent& key_event) {
   return key_event.key_code() == ui::VKEY_TAB && !key_event.IsControlDown();
 }
 
 void FocusManager::ViewRemoved(View* removed) {
   // If the view being removed contains (or is) the focused view,
   // clear the focus.  However, it's not safe to call ClearFocus()
   // (and in turn ClearNativeFocus()) here because ViewRemoved() can
   // be called while the top level widget is being destroyed.
-  if (focused_view_ && removed->Contains(focused_view_))
+  if (focused_view_ && removed && removed->Contains(focused_view_))

[sky, 2016/06/06 16:30:45]

This code shouldn't have to check for a null supplied view. This code should
have a DCHECK(removed) and callers shouldn't supply null.

     SetFocusedView(NULL);
 }
 
 void FocusManager::AddFocusChangeListener(FocusChangeListener* listener) {
   focus_change_listeners_.AddObserver(listener);
 }
 
 void FocusManager::RemoveFocusChangeListener(FocusChangeListener* listener) {
   focus_change_listeners_.RemoveObserver(listener);
 }
@@ skipping 21 matching lines @@
 // |keyboard_accessible_| is only used on Mac.
 #if defined(OS_MACOSX)
   return keyboard_accessible_ ? view->IsAccessibilityFocusable()
                               : view->IsFocusable();
 #else
   return view->IsAccessibilityFocusable();
 #endif
 }
 
 }  // namespace views