Enforce the 'requirements' field in manifests.

chrome/browser/download/download_crx_util.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.
 //
 // Download code which handles CRX files (extensions, themes, apps, ...).
 
 #include "chrome/browser/download/download_util.h"
 #include "chrome/browser/extensions/crx_installer.h"
 #include "chrome/browser/extensions/extension_install_prompt.h"
 #include "chrome/browser/extensions/extension_service.h"
@@ skipping 65 matching lines @@
 
   ExtensionService* service = profile->GetExtensionService();
   CHECK(service);
 
   scoped_refptr<extensions::CrxInstaller> installer(
       extensions::CrxInstaller::Create(
           service,
           CreateExtensionInstallPrompt(profile),
           WebstoreInstaller::GetAssociatedApproval(download_item)));
 
+  installer->set_error_on_unsported_requirements(true);
   installer->set_delete_source(true);
   installer->set_install_cause(extension_misc::INSTALL_CAUSE_USER_DOWNLOAD);
 
   if (OffStoreInstallAllowedByPrefs(profile, download_item)) {
     installer->set_off_store_install_allow_reason(
         extensions::CrxInstaller::OffStoreInstallAllowedBecausePref);
   }
 
   if (extensions::UserScript::IsURLUserScript(download_item.GetURL(),
                                               download_item.GetMimeType())) {
@@ skipping 23 matching lines @@
   if (download_item.GetMimeType() == extensions::Extension::kMimeType ||
       extensions::UserScript::IsURLUserScript(download_item.GetURL(),
                                               download_item.GetMimeType())) {
     return true;
   } else {
     return false;
   }
 }
 
 }  // namespace download_crx_util