Reland of Supervised Users: Create ResourceThrottle only if filtering is enabled

chrome/browser/supervised_user/supervised_user_resource_throttle_browsertest.cc

 // Copyright 2014 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/supervised_user/supervised_user_resource_throttle.h"
 
 #include <memory>
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 119 matching lines @@
   // Both iframes (from allowed host iframe1.com as well as from blocked host
   // iframe2.com) should be loaded normally, since we don't filter iframes
   // (yet) - see crbug.com/651115.
   bool loaded1 = false;
   ASSERT_TRUE(content::ExecuteScriptAndExtractBool(tab, "loaded1()", &loaded1));
   EXPECT_TRUE(loaded1);
   bool loaded2 = false;
   ASSERT_TRUE(content::ExecuteScriptAndExtractBool(tab, "loaded2()", &loaded2));
   EXPECT_TRUE(loaded2);
 }
+
+class SupervisedUserResourceThrottleNotSupervisedTest
+    : public SupervisedUserResourceThrottleTest {
+ protected:
+  SupervisedUserResourceThrottleNotSupervisedTest() {}
+  ~SupervisedUserResourceThrottleNotSupervisedTest() override {}
+
+ private:
+  // Overridden to do nothing, so that the supervised user ID will be empty.
+  void SetUpCommandLine(base::CommandLine* command_line) override {}
+};
+
+IN_PROC_BROWSER_TEST_F(SupervisedUserResourceThrottleNotSupervisedTest,
+                       DontBlock) {
+  BlockHost(kExampleHost);
+
+  WebContents* tab = browser()->tab_strip_model()->GetActiveWebContents();
+
+  GURL blocked_url = embedded_test_server()->GetURL(
+      kExampleHost, "/supervised_user/simple.html");
+  ui_test_utils::NavigateToURL(browser(), blocked_url);
+  // Even though the URL is marked as blocked, the load should go through, since
+  // the user isn't supervised.
+  EXPECT_FALSE(tab->ShowingInterstitialPage());
+}