Reauthenticate the user before launching Smart Lock setup app.

chrome/browser/chromeos/login/easy_unlock/short_lived_user_context.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/easy_unlock/short_lived_user_context.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/task_runner.h"
+#include "chrome/common/extensions/extension_constants.h"
+#include "chromeos/login/auth/user_context.h"
+
+namespace chromeos {
+
+namespace {
+
+// The number of minutes that the user context will be stored.
+const int64 kUserContextTimeToLiveMinutes = 10;
+
+}  // namespace
+
+ShortLivedUserContext::ShortLivedUserContext(
+    const UserContext& user_context,
+    apps::AppLifetimeMonitor* app_lifetime_monitor,
+    base::TaskRunner* task_runner)
+    : user_context_(new UserContext(user_context)),
+      app_lifetime_monitor_(app_lifetime_monitor),
+      weak_ptr_factory_(this) {
+  app_lifetime_monitor_->AddObserver(this);
+
+  task_runner->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&ShortLivedUserContext::DeleteUserContext,
+                 weak_ptr_factory_.GetWeakPtr()),
+      base::TimeDelta::FromMinutes(kUserContextTimeToLiveMinutes));
+}
+
+ShortLivedUserContext::~ShortLivedUserContext() {
+  DeleteUserContext();
+}
+
+void ShortLivedUserContext::DeleteUserContext() {
+  if (user_context_.get()) {
+    user_context_->ClearSecrets();
+    user_context_.reset();
+    app_lifetime_monitor_->RemoveObserver(this);

[tbarzic, 2014/11/01 23:21:45]

this doesn't really belong in "DeleteUserContext"
Maybe you could rename the method to Reset, or move RemoveObserver to dtor.

[Tim Song, 2014/11/03 19:10:43]

Done. Renamed to Reset().

+  }
+}
+
+void ShortLivedUserContext::OnAppDeactivated(Profile* profile,
+                                             const std::string& app_id) {
+  if (app_id == extension_misc::kEasyUnlockAppId)
+    DeleteUserContext();
+}
+
+}  // namespace chromeos