Use PreloadCheckGroup in ExtensionInstallChecker. Make RequirementsChecker a PreloadCheck.

chrome/browser/extensions/crx_installer_browsertest.cc

 // Copyright (c) 2012 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/extensions/crx_installer.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 271 matching lines @@
     crx_installer->set_error_on_unsupported_requirements(true);
     crx_installer->InstallWebApp(
         CreateWebAppInfo(kAppTitle, kAppDescription, kAppUrl, 64));
     EXPECT_TRUE(WaitForCrxInstallerDone());
     ASSERT_TRUE(crx_installer->extension());
     ASSERT_FALSE(HasRequirementErrors(crx_installer.get()));
     ASSERT_FALSE(HasPolicyErrors(crx_installer.get()));
   }
 
   bool HasRequirementErrors(CrxInstaller* crx_installer) {
-    return !crx_installer->install_checker_.requirement_errors().empty();
+    return !crx_installer->install_checker_.requirement_error_message().empty();
   }
 
   bool HasPolicyErrors(CrxInstaller* crx_installer) {
     return !crx_installer->install_checker_.policy_error().empty();
   }
 };
 
 class ExtensionCrxInstallerTestWithExperimentalApis
     : public ExtensionCrxInstallerTest {
  protected:
@@ skipping 418 matching lines @@
     EXPECT_TRUE(WaitForCrxInstallerDone());
     const Extension* extension = installer->extension();
     ASSERT_TRUE(extension);
     ASSERT_EQ(extension_id, extension->id());
     EXPECT_TRUE(ExtensionPrefs::Get(profile())->AllowFileAccess(extension_id));
     EXPECT_TRUE(extension->creation_flags() & Extension::ALLOW_FILE_ACCESS);
   }
 }
 
 }  // namespace extensions