Reenable ExtensionWebRequestApiTest.WebRequestBlocking after fixing the flakyness

chrome/browser/extensions/extension_webrequest_apitest.cc

 // Copyright (c) 2011 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 "base/command_line.h"
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_webrequest_api.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
@@ skipping 72 matching lines @@
 IN_PROC_BROWSER_TEST_F(ExtensionWebRequestApiTest, WebRequestAuthRequired) {
   CommandLine::ForCurrentProcess()->AppendSwitch(
       switches::kEnableExperimentalExtensionApis);
 
   CancelLoginDialog login_dialog_helper;
 
   ASSERT_TRUE(RunExtensionSubtest("webrequest", "test_auth_required.html")) <<
       message_;
 }
 
-// Hangs flakily: http://crbug.com/91715
 IN_PROC_BROWSER_TEST_F(ExtensionWebRequestApiTest,
-                       DISABLED_WebRequestBlocking) {
+                       WebRequestBlocking) {
   CommandLine::ForCurrentProcess()->AppendSwitch(
       switches::kEnableExperimentalExtensionApis);
 
   ASSERT_TRUE(RunExtensionSubtest("webrequest", "test_blocking.html")) <<
       message_;
 }
 
 IN_PROC_BROWSER_TEST_F(ExtensionWebRequestApiTest, WebRequestNewTab) {
   CommandLine::ForCurrentProcess()->AppendSwitch(
       switches::kEnableExperimentalExtensionApis);
@@ skipping 21 matching lines @@
   mouse_event.button = WebKit::WebMouseEvent::ButtonLeft;
   mouse_event.x = 7;
   mouse_event.y = 7;
   mouse_event.clickCount = 1;
   tab->render_view_host()->ForwardMouseEvent(mouse_event);
   mouse_event.type = WebKit::WebInputEvent::MouseUp;
   tab->render_view_host()->ForwardMouseEvent(mouse_event);
 
   ASSERT_TRUE(catcher.GetNextResult()) << catcher.message();
 }