Enable login screen apps.

chrome/browser/extensions/external_provider_impl.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/external_provider_impl.h"
 
 #include <stddef.h>
 
 #include <set>
 #include <vector>
@@ skipping 122 matching lines @@
     service_->OnExternalExtensionUpdateUrlFound(*extension, true);
 
   for (const auto& extension : external_file_extensions)
     service_->OnExternalExtensionFileFound(*extension);
 
   service_->OnExternalProviderReady(this);
 }
 
 void ExternalProviderImpl::UpdatePrefs(base::DictionaryValue* prefs) {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  // We only expect updates from windows registry.
-  CHECK(crx_location_ == Manifest::EXTERNAL_REGISTRY);
+  // We only expect updates from windows registry or via policies on chromeos.
+  CHECK(crx_location_ == Manifest::EXTERNAL_REGISTRY ||
+        download_location_ == Manifest::EXTERNAL_POLICY_DOWNLOAD);
 
   // Check if the service is still alive. It is possible that it went
   // away while |loader_| was working on the FILE thread.
   if (!service_)
     return;
 
   std::set<std::string> removed_extensions;
   // Find extensions that were removed by this ExternalProvider.
   for (base::DictionaryValue::Iterator i(*prefs_); !i.IsAtEnd(); i.Advance()) {
     const std::string& extension_id = i.key();
@@ skipping 335 matching lines @@
 // static
 void ExternalProviderImpl::CreateExternalProviders(
     VisitorInterface* service,
     Profile* profile,
     ProviderCollection* provider_list) {
   TRACE_EVENT0("browser,startup",
                "ExternalProviderImpl::CreateExternalProviders");
   scoped_refptr<ExternalLoader> external_loader;
   scoped_refptr<ExternalLoader> external_recommended_loader;
   extensions::Manifest::Location crx_location = Manifest::INVALID_LOCATION;
+
 #if defined(OS_CHROMEOS)
+  if (chromeos::ProfileHelper::IsSigninProfile(profile)) {
+    // Download apps installed by policy in the login profile. Flags
+    // FROM_WEBSTORE/WAS_INSTALLED_BY_DEFAULT are applied because these apps are
+    // downloaded from the webstore, and we want to treat them as built-in
+    // extensions.

[achuithb, 2017/03/22 00:15:53]

Let me know if you have better wording for this or would like me to move these
comments elsewhere.

+    external_loader = new ExternalPolicyLoader(
+        ExtensionManagementFactory::GetForBrowserContext(profile),
+        ExternalPolicyLoader::FORCED);
+    provider_list->push_back(base::MakeUnique<ExternalProviderImpl>(
+        service, external_loader, profile, crx_location,
+        Manifest::EXTERNAL_POLICY_DOWNLOAD,
+        Extension::FROM_WEBSTORE | Extension::WAS_INSTALLED_BY_DEFAULT));
+    return;
+  }
+
   policy::BrowserPolicyConnectorChromeOS* connector =
       g_browser_process->platform_part()->browser_policy_connector_chromeos();
   bool is_chrome_os_public_session = false;
   const user_manager::User* user =
       chromeos::ProfileHelper::Get()->GetUserByProfile(profile);
   policy::DeviceLocalAccount::Type account_type;
   if (user && connector->IsEnterpriseManaged() &&
       policy::IsDeviceLocalAccountUser(user->GetAccountId().GetUserEmail(),
                                        &account_type)) {
     if (account_type == policy::DeviceLocalAccount::TYPE_PUBLIC_SESSION)
@@ skipping 184 matching lines @@
     provider_list->push_back(std::move(drive_migration_provider));
   }
 
   provider_list->push_back(base::MakeUnique<ExternalProviderImpl>(
       service, new ExternalComponentLoader(profile), profile,
       Manifest::INVALID_LOCATION, Manifest::EXTERNAL_COMPONENT,
       Extension::FROM_WEBSTORE | Extension::WAS_INSTALLED_BY_DEFAULT));
 }
 
 }  // namespace extensions