Do some null-checks to make sure removing an app on ash works correctly

chrome/browser/ui/views/extensions/extension_uninstall_dialog_view.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 "chrome/browser/extensions/extension_uninstall_dialog.h"
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
@@ skipping 28 matching lines @@
 // use the given browser window.
 // Note this function could return NULL if ash app list is not visible and
 // there is no browser window.
 gfx::NativeWindow GetParent(Browser* browser) {
 #if defined(USE_ASH)
   gfx::NativeWindow app_list = ash::Shell::GetInstance()->GetAppListWindow();
   if (app_list)
     return app_list;
 #endif
 
-  if (browser->window())
+  if (browser && browser->window())
     return browser->window()->GetNativeWindow();
 
   return NULL;
 }
 
 // Views implementation of the uninstall dialog.
 class ExtensionUninstallDialogViews : public ExtensionUninstallDialog {
  public:
   ExtensionUninstallDialogViews(Browser* browser,
                                 ExtensionUninstallDialog::Delegate* delegate);
@@ skipping 64 matching lines @@
 ExtensionUninstallDialogViews::~ExtensionUninstallDialogViews() {
   // Close the widget (the views framework will delete view_).
   if (view_) {
     view_->DialogDestroyed();
     view_->GetWidget()->CloseNow();
   }
 }
 
 void ExtensionUninstallDialogViews::Show() {
   gfx::NativeWindow parent = GetParent(browser_);
-  if (!parent) {
+  if (browser_ && !parent) {
     delegate_->ExtensionUninstallCanceled();
     return;
   }
 
   view_ = new ExtensionUninstallDialogDelegateView(this, extension_, &icon_);
   views::Widget::CreateWindowWithParent(view_, parent)->Show();
 }
 
 void ExtensionUninstallDialogViews::ExtensionUninstallAccepted() {
   // The widget gets destroyed when the dialog is accepted.
@@ skipping 92 matching lines @@
   }
 }
 
 }  // namespace
 
 // static
 ExtensionUninstallDialog* ExtensionUninstallDialog::Create(
     Browser* browser, Delegate* delegate) {
   return new ExtensionUninstallDialogViews(browser, delegate);
 }