Modify PnaclHeaderTest to run w/ an empty PNaCl component dir.

chrome/test/nacl/pnacl_header_test.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 "chrome/test/nacl/pnacl_header_test.h"
 
 #include "base/bind.h"
 #include "base/path_service.h"
+#include "base/test/scoped_path_override.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "chrome/test/nacl/nacl_browsertest_util.h"
 #include "content/public/browser/web_contents.h"
 #include "net/test/embedded_test_server/embedded_test_server.h"
 #include "net/test/embedded_test_server/http_request.h"
 #include "net/test/embedded_test_server/http_response.h"
 
@@ skipping 19 matching lines @@
 }
 
 void PnaclHeaderTest::RunLoadTest(const std::string& url,
                                   int expected_noncors,
                                   int expected_cors) {
   StartServer();
   LoadTestMessageHandler handler;
   content::JavascriptTestObserver observer(
       browser()->tab_strip_model()->GetActiveWebContents(),
       &handler);
+
+  // Make sure this is able to do a pexe fetch, even without access
+  // to the PNaCl component files (make DIR_PNACL_COMPONENT empty).
+  // The pexe fetch that is done with special headers must be able to
+  // start before the component files are on disk. This is because it
+  // is the pexe fetch that helps trigger an on-demand installation
+  // which installs the files to disk (if that hasn't already happened
+  // in the background).
+  base::ScopedPathOverride component_dir(chrome::DIR_PNACL_COMPONENT);
+
   ui_test_utils::NavigateToURL(browser(), embedded_test_server()->GetURL(url));
   // Wait until the NMF and pexe are also loaded, not just the HTML.
   // Do this by waiting till the LoadTestMessageHandler responds.
   EXPECT_TRUE(observer.Run()) << handler.error_message();
   EXPECT_TRUE(handler.test_passed()) << "Test failed.";
   EXPECT_EQ(expected_noncors, noncors_loads_);
   EXPECT_EQ(expected_cors, cors_loads_);
 }
 
 scoped_ptr<HttpResponse> PnaclHeaderTest::WatchForPexeFetch(
@@ skipping 37 matching lines @@
   http_response->set_code(net::HTTP_NOT_FOUND);
   http_response->set_content("PEXE ... not found");
   http_response->set_content_type("application/octet-stream");
   return http_response.PassAs<HttpResponse>();
 }
 
 IN_PROC_BROWSER_TEST_F(PnaclHeaderTest, TestHasPnaclHeader) {
   // Load 2 pexes, one same origin and one cross orgin.
   RunLoadTest("/nacl/pnacl_request_header/pnacl_request_header.html", 1, 1);
 }