Re-land MD Settings fix for crash on back/forward navigation

chrome/browser/ui/webui/settings/md_settings_ui_browsertest.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 <string>
 
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_commands.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "content/public/common/url_constants.h"
+#include "content/public/test/browser_test_utils.h"
+#include "ui/base/window_open_disposition.h"
 #include "url/gurl.h"
 
 typedef InProcessBrowserTest MdSettingsBrowserTest;
 
+using ui_test_utils::NavigateToURL;
+using content::WaitForLoadStop;
+
 IN_PROC_BROWSER_TEST_F(MdSettingsBrowserTest, ViewSourceDoesntCrash) {
-  ui_test_utils::NavigateToURL(browser(),
+  NavigateToURL(browser(),
       GURL(content::kViewSourceScheme + std::string(":") +
            chrome::kChromeUIMdSettingsURL));
 }
+
+// May not complete on memory bots. TODO(dbeam): investigate and fix.
+// See https://crbug.com/558434 and https://crbug.com/620370.
+#if defined(MEMORY_SANITIZER)
+#define MAYBE_BackForwardDoesntCrash DISABLED_BackForwardDoesntCrash
+#else
+#define MAYBE_BackForwardDoesntCrash BackForwardDoesntCrash
+#endif
+
+IN_PROC_BROWSER_TEST_F(MdSettingsBrowserTest, MAYBE_BackForwardDoesntCrash) {
+  NavigateToURL(browser(), GURL(chrome::kChromeUIMdSettingsURL));
+
+  NavigateToURL(browser(), GURL(chrome::kChromeUINewTabURL));
+
+  chrome::GoBack(browser(), CURRENT_TAB);
+  WaitForLoadStop(browser()->tab_strip_model()->GetActiveWebContents());
+}