Add a browser test for access control for file: scheme

chrome/browser/net/errorpage_browsertest.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 <memory>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
@@ skipping 71 matching lines @@
 #endif
 #include "components/policy/core/common/mock_configuration_policy_provider.h"
 
 using content::BrowserThread;
 using content::NavigationController;
 using net::URLRequestFailedJob;
 using net::URLRequestTestJob;
 
 namespace {
 
-// Returns true if |text| is displayed on the page |browser| is currently
-// displaying.  Uses "innerText", so will miss hidden text, and whitespace
-// space handling may be weird.
+// Searches for first node containing |text|, and if it finds one, searches
+// through all ancestors seeing if any of them is of class "hidden". Since it
+// relies on the hidden class used by network error pages, not suitable for
+// general use.
 bool WARN_UNUSED_RESULT IsDisplayingText(Browser* browser,
                                          const std::string& text) {
   // clang-format off
   std::string command = base::StringPrintf(R"(
     function isNodeVisible(node) {
       if (!node || node.classList.contains('hidden'))
         return false;
       if (!node.parentElement)
         return true;
       // Otherwise, we must check all parent nodes
@@ skipping 1451 matching lines @@
                        Http09WeirdPortEnabled) {
   const char kHttp09Response[] = "JumboShrimp";
   ASSERT_TRUE(embedded_test_server()->Start());
   ui_test_utils::NavigateToURL(
       browser(), embedded_test_server()->GetURL(std::string("/echo-raw?") +
                                                 kHttp09Response));
   EXPECT_TRUE(IsDisplayingText(browser(), kHttp09Response));
 }
 
 }  // namespace