Fix DCHECK failure when Manifest fetch has an Access Control error.

content/browser/manifest/manifest_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 "base/command_line.h"
 #include "base/path_service.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/manifest.h"
 #include "content/public/test/browser_test_utils.h"
@@ skipping 230 matching lines @@
 
   std::string manifest_url = cors_embedded_test_server()->GetURL(
       "/manifest/dummy-manifest.json").spec();
   ASSERT_TRUE(content::ExecuteScript(shell()->web_contents(),
                                      "setManifestTo('" + manifest_url + "')"));
 
   GetManifestAndWait();
   EXPECT_TRUE(manifest().IsEmpty());
 
   EXPECT_EQ(0u, console_error_count());
+
+  // The purpose of this second load is to make sure the first load is fully
+  // finished. The first load will fail because of Access Control error but the
+  // underlying Blink loader will continue fetching the file. There is no
+  // reliable way to know when the fetch is finished from the browser test
+  // except by fetching the same file from same origin, making it succeed when
+  // it is actually fully loaded.
+  manifest_url =
+      embedded_test_server()->GetURL("/manifest/dummy-manifest.json").spec();
+  ASSERT_TRUE(content::ExecuteScript(shell()->web_contents(),
+                                     "setManifestTo('" + manifest_url + "')"));
+  GetManifestAndWait();
 }
 
 // If a page's manifest lives in a different origin, it should be accessible if
 // it has valid access controls headers.
 IN_PROC_BROWSER_TEST_F(ManifestBrowserTest, CORSManifestWithAcessControls) {
   ASSERT_TRUE(embedded_test_server()->InitializeAndWaitUntilReady());
   ASSERT_TRUE(cors_embedded_test_server()->InitializeAndWaitUntilReady());
   ASSERT_NE(embedded_test_server()->port(),
             cors_embedded_test_server()->port());
 
@@ skipping 136 matching lines @@
         "document.body.appendChild(a); a.click();"));
     navigation_observer.Wait();
   }
 
   GetManifestAndWait();
   EXPECT_FALSE(manifest().IsEmpty());
   EXPECT_EQ(0u, console_error_count());
 }
 
 } // namespace content