Fix AppModalDialogHelper to deal with a TabStrip without an active tab

chrome/browser/ui/views/chrome_javascript_native_dialog_factory_views.cc

 // Copyright 2014 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/ui/app_modal/chrome_javascript_native_dialog_factory.h"
 
 #include "components/app_modal/javascript_dialog_manager.h"
 #include "components/app_modal/javascript_native_dialog_factory.h"
 #include "components/constrained_window/constrained_window_views.h"
 
 #if defined(USE_X11) && !defined(OS_CHROMEOS)
 #include "chrome/browser/ui/views/javascript_app_modal_dialog_views_x11.h"
 #else
 #include "chrome/browser/ui/blocked_content/app_modal_dialog_helper.h"
 #include "components/app_modal/javascript_app_modal_dialog.h"
 #include "components/app_modal/views/javascript_app_modal_dialog_views.h"
 #endif
 
 namespace {
 
 #if !defined(USE_X11) || defined(OS_CHROMEOS)
 class ChromeJavaScriptAppModalDialogViews
     : public app_modal::JavaScriptAppModalDialogViews {
  public:
   explicit ChromeJavaScriptAppModalDialogViews(
       app_modal::JavaScriptAppModalDialog* parent)
       : app_modal::JavaScriptAppModalDialogViews(parent),
-        helper_(new AppModalDialogHelper(parent->web_contents())) {}
+        helper_(
+            new AppModalDialogHelper(parent ? parent->web_contents() : NULL)) {}

[Bernhard Bauer, 2014/12/22 13:18:35]

nullptr

   virtual ~ChromeJavaScriptAppModalDialogViews() {}
 
  private:
   scoped_ptr<AppModalDialogHelper> helper_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeJavaScriptAppModalDialogViews);
 };
 #endif
 
 class ChromeJavaScriptNativeDialogViewsFactory
@@ skipping 19 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(ChromeJavaScriptNativeDialogViewsFactory);
 };
 
 }  // namespace
 
 void InstallChromeJavaScriptNativeDialogFactory() {
   app_modal::JavaScriptDialogManager::GetInstance()->
       SetNativeDialogFactory(
           make_scoped_ptr(new ChromeJavaScriptNativeDialogViewsFactory));
 }