Fix integration tests in src/chrome and src/extensions so that we can turn on IO thread checks wi...

chrome/browser/downgrade/user_data_downgrade_browsertest.cc

 // Copyright 2016 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/downgrade/user_data_downgrade.h"
 
 #include "base/files/file_util.h"
 #include "base/path_service.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/test_reg_util_win.h"
 #include "base/threading/sequenced_worker_pool.h"
+#include "base/threading/thread_restrictions.h"
 #include "base/version.h"
 #include "base/win/registry.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/installer/util/browser_distribution.h"
 #include "chrome/installer/util/google_update_constants.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "content/public/browser/browser_thread.h"
 
 namespace downgrade {
@@ skipping 86 matching lines @@
  protected:
   // InProcessBrowserTest:
   bool SetUpUserDataDirectory() override {
     return CreateTemporaryFileInDir(user_data_dir_, &other_file_);
   }
 };
 
 // Verify the user data directory has been renamed and created again after
 // downgrade.
 IN_PROC_BROWSER_TEST_F(UserDataDowngradeBrowserCopyAndCleanTest, Test) {
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
   content::BrowserThread::GetBlockingPool()->FlushForTesting();
   EXPECT_EQ(chrome::kChromeVersion, GetLastVersion(user_data_dir_).GetString());
   ASSERT_FALSE(base::PathExists(other_file_));
 }
 
 // Verify the user data directory will not be reset without downgrade.
 IN_PROC_BROWSER_TEST_F(UserDataDowngradeBrowserNoResetTest, Test) {
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
   EXPECT_EQ(chrome::kChromeVersion, GetLastVersion(user_data_dir_).GetString());
   ASSERT_TRUE(base::PathExists(other_file_));
 }
 
 // Verify the "Last Version" file won't be created for non-msi install.
 IN_PROC_BROWSER_TEST_F(UserDataDowngradeBrowserNoMSITest, Test) {
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
   ASSERT_FALSE(base::PathExists(last_version_file_path_));
   ASSERT_TRUE(base::PathExists(other_file_));
 }
 
 }  // namespace downgrade