Fix CrossProcessPopupInheritsSandboxFlagsWithNoOpener on M50 official builds.

content/browser/frame_host/render_frame_host_manager_browsertest.cc

 // Copyright 2013 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 <stddef.h>
 #include <stdint.h>
 
 #include <set>
 
 #include "base/command_line.h"
@@ skipping 2495 matching lines @@
         "frame.sandbox = 'allow-scripts allow-popups';\n"
         "document.body.appendChild(frame);\n";
     EXPECT_TRUE(ExecuteScript(shell()->web_contents(), script));
   }
 
   // Navigate iframe to a page with target=_blank links, and rewrite the links
   // to point to valid cross-site URLs.
   GURL frame_url(
       embedded_test_server()->GetURL("a.com", "/click-noreferrer-links.html"));
   NavigateFrameToURL(root->child_at(0), frame_url);
+  EXPECT_TRUE(WaitForLoadStop(shell()->web_contents()));
   std::string script = "setOriginForLinks('http://b.com:" +
                        embedded_test_server()->base_url().port() + "/');";
   EXPECT_TRUE(ExecuteScript(root->child_at(0)->current_frame_host(), script));
 
   // Helper to click on the 'rel=noreferrer target=_blank' and 'rel=noopener
   // target=_blank' links.  Checks that these links open a popup that ends up
   // in a new SiteInstance even without site-per-process and then verifies that
   // the popup is still sandboxed.
   auto click_link_and_verify_popup = [this,
                                       root](std::string link_opening_script) {
@@ skipping 17 matching lines @@
         new_shell->web_contents(),
         "domAutomationController.send(document.origin)", &origin));
     EXPECT_EQ("null", origin);
   };
 
   click_link_and_verify_popup("clickNoOpenerTargetBlankLink()");
   click_link_and_verify_popup("clickNoRefTargetBlankLink()");
 }
 
 }  // namespace content