Turn on auto-dismissing dialogs for trunk builds.

chrome/browser/ui/javascript_dialogs/javascript_dialog_tab_helper.cc

 // Copyright 2016 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/javascript_dialogs/javascript_dialog_tab_helper.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/feature_list.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 70 matching lines @@
   if (dialog_) {
     CloseDialog(false, base::string16(), DismissalCause::TAB_HELPER_DESTROYED);
   }
 }
 
 void JavaScriptDialogTabHelper::SetDialogShownCallbackForTesting(
     base::Closure callback) {
   dialog_shown_ = callback;
 }
 
+bool JavaScriptDialogTabHelper::IsShowingDialogForTesting() const {
+  return !!dialog_;
+}
+
 void JavaScriptDialogTabHelper::RunJavaScriptDialog(
     content::WebContents* alerting_web_contents,
     const GURL& origin_url,
     content::JavaScriptDialogType dialog_type,
     const base::string16& message_text,
     const base::string16& default_prompt_text,
     const DialogClosedCallback& callback,
     bool* did_suppress_message) {
   SiteEngagementService* site_engagement_service = SiteEngagementService::Get(
       Profile::FromBrowserContext(alerting_web_contents->GetBrowserContext()));
@@ skipping 243 matching lines @@
   dialog_callback_.Run(success, user_input);
 
   ClearDialogInfo();
 }
 
 void JavaScriptDialogTabHelper::ClearDialogInfo() {
   dialog_.reset();
   dialog_callback_.Reset();
   BrowserList::RemoveObserver(this);
 }