Do not reload account picker when device-local account policy changes

chrome/browser/chromeos/login/screens/chrome_user_selection_screen.cc

+// Copyright 2014 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/chromeos/login/screens/chrome_user_selection_screen.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/message_loop/message_loop.h"
+#include "base/strings/utf_string_conversions.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/browser_process_platform_part.h"
+#include "chrome/browser/chromeos/login/users/user_manager.h"
+#include "chrome/browser/chromeos/policy/browser_policy_connector_chromeos.h"
+#include "chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h"
+#include "components/user_manager/user.h"
+#include "components/user_manager/user_type.h"
+
+namespace chromeos {
+
+ChromeUserSelectionScreen::ChromeUserSelectionScreen()
+    : handler_initialized_(false),
+      weak_factory_(this) {
+  device_local_account_policy_service_ = g_browser_process->platform_part()->
+      browser_policy_connector_chromeos()->GetDeviceLocalAccountPolicyService();
+  device_local_account_policy_service_->AddObserver(this);
+}
+
+ChromeUserSelectionScreen::~ChromeUserSelectionScreen() {
+  device_local_account_policy_service_->RemoveObserver(this);
+}
+
+void ChromeUserSelectionScreen::Init(const user_manager::UserList& users,
+                                     bool show_guest) {
+  UserSelectionScreen::Init(users, show_guest);
+
+  // Retrieve the current policy for |users_|.
+  for (user_manager::UserList::const_iterator it = users_.begin();

[Nikita (slow), 2014/08/05 12:09:24]

nit: You may as well add GetUsers() getter.

[bartfab (slow), 2014/08/05 18:52:02]

Sorry, I do not understand. Where would you like me to add this getter? If you
mean UserManager - I think passing in dependencies rather than reaching out to
singletons like UserManager is actually better.

[Nikita (slow), 2014/08/06 08:14:40]

I mean instead of having users_ as a protected field in UserSelectionScreen you
may instead just expose it through the getter.

[bartfab (slow), 2014/08/07 14:14:50]

Thanks, somehow I did not realize that:
a) using a getter makes sense here,
b) the getter even exists already,
and finnally,
c) this method actually knows the |users| already and does need to read them
form anywhere.

Doh. I uploaded follow-up CL 446383002 for this.

+       it != users_.end(); ++it) {
+    if ((*it)->GetType() == user_manager::USER_TYPE_PUBLIC_ACCOUNT)
+      OnPolicyUpdated((*it)->GetUserID());
+  }
+}
+
+void ChromeUserSelectionScreen::SendUserList() {
+  UserSelectionScreen::SendUserList();
+  handler_initialized_ = true;
+}
+
+void ChromeUserSelectionScreen::OnPolicyUpdated(const std::string& user_id) {
+  policy::DeviceLocalAccountPolicyBroker* broker =
+      device_local_account_policy_service_->GetBrokerForUser(user_id);
+  if (!broker)
+    return;
+
+  CheckForPublicSessionDisplayNameChange(broker);
+}
+
+void ChromeUserSelectionScreen::OnDeviceLocalAccountsChanged() {
+  // Nothing to do here. When the list of device-local accounts changes, the
+  // entire UI is reloaded.
+}
+
+void ChromeUserSelectionScreen::CheckForPublicSessionDisplayNameChange(
+    policy::DeviceLocalAccountPolicyBroker* broker) {
+  const std::string& user_id = broker->user_id();
+  const std::string& display_name = broker->GetDisplayName();
+  if (display_name == public_session_display_names_[user_id])
+    return;
+
+  public_session_display_names_[user_id] = display_name;
+
+  if (!handler_initialized_)
+    return;
+
+  if (!display_name.empty()) {
+    // If a new display name was set by policy, notify the UI about it.
+    handler_->SetPublicSessionDisplayName(user_id, display_name);
+    return;
+  }
+
+  // When no display name is set by policy, the |User|, owned by |UserManager|,
+  // decides what display name to use. However, the order in which |UserManager|
+  // and |this| are informed of the display name change is undefined. Post a
+  // task that will update the UI after the UserManager is guaranteed to have
+  // been informed of the change.
+  base::MessageLoop::current()->PostTask(
+      FROM_HERE,
+      base::Bind(&ChromeUserSelectionScreen::SetPublicSessionDisplayName,
+                 weak_factory_.GetWeakPtr(),
+                 user_id));
+}
+
+void ChromeUserSelectionScreen::SetPublicSessionDisplayName(
+    const std::string& user_id) {
+  const user_manager::User* user = UserManager::Get()->FindUser(user_id);
+  if (!user || user->GetType() != user_manager::USER_TYPE_PUBLIC_ACCOUNT)
+    return;
+
+  handler_->SetPublicSessionDisplayName(
+      user_id,
+      base::UTF16ToUTF8(user->GetDisplayName()));
+}
+
+}  // namespace chromeos