Make show_dialog_callback optional in ExtensionInstallPrompt

chrome/browser/extensions/extension_install_prompt.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_install_prompt.h"
 
 #include <map>
 
 #include "base/command_line.h"
 #include "base/file_util.h"
@@ skipping 384 matching lines @@
 void ExtensionInstallPrompt::ConfirmInstall(
     Delegate* delegate,
     const Extension* extension,
     const ShowDialogCallback& show_dialog_callback) {
   DCHECK(ui_loop_ == MessageLoop::current());
   extension_ = extension;
   permissions_ = extension->GetActivePermissions();
   delegate_ = delegate;
   prompt_type_ = INSTALL_PROMPT;
   show_dialog_callback_ = show_dialog_callback;
-  DCHECK(!show_dialog_callback_.is_null());
 
   // We special-case themes to not show any confirm UI. Instead they are
   // immediately installed, and then we show an infobar (see OnInstallSuccess)
   // to allow the user to revert if they don't like it.
   //
   // We don't do this in the case where off-store extension installs are
   // disabled because in that case, we don't show the dangerous download UI, so
   // we need the UI confirmation.
   if (extension->is_theme()) {
     if (extension->from_webstore() ||
@@ skipping 166 matching lines @@
       break;
     }
     default:
       NOTREACHED() << "Unknown message";
       return;
   }
 
   if (AutoConfirmPrompt(delegate_))
     return;
 
-  DCHECK(!show_dialog_callback_.is_null());
-  show_dialog_callback_.Run(parent_, navigator_, delegate_, prompt_);
+  if (show_dialog_callback_.is_null())
+    GetDefaultShowDialogCallback().Run(parent_, navigator_, delegate_, prompt_);
+  else
+    show_dialog_callback_.Run(parent_, navigator_, delegate_, prompt_);
 }
 
 namespace chrome {
 
 ExtensionInstallPrompt* CreateExtensionInstallPromptWithBrowser(
     Browser* browser) {
   // |browser| can be NULL in unit tests.
   if (!browser)
     return new ExtensionInstallPrompt(NULL, NULL, NULL);
   gfx::NativeWindow parent =
       browser->window() ? browser->window()->GetNativeWindow() : NULL;
   return new ExtensionInstallPrompt(parent, browser, browser->profile());
 }
 
 }  // namespace chrome