easy-unlock: Fix AttemptAuth email CHECK crash

chrome/browser/signin/easy_unlock_service.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/signin/easy_unlock_service.h"
 
 #include "apps/app_lifetime_monitor.h"
 #include "apps/app_lifetime_monitor_factory.h"
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 475 matching lines @@
 
   return handler->state();
 }
 
 void EasyUnlockService::AttemptAuth(const std::string& user_id) {
   AttemptAuth(user_id, AttemptAuthCallback());
 }
 
 void EasyUnlockService::AttemptAuth(const std::string& user_id,
                                     const AttemptAuthCallback& callback) {
-  CHECK_EQ(GetUserEmail(), user_id);
+  const std::string user_email = GetUserEmail();
+  if (user_email.empty()) {
+    LOG(ERROR) << "Empty user email. Refresh token might go bad.";
+    return;

[Tim Song, 2015/05/21 00:06:46]

We should run the callback with a failure.

[xiyuan, 2015/05/21 01:32:12]

Good call. Done.

+  }
+
+  CHECK_EQ(user_email, user_id);
 
   auth_attempt_.reset(new EasyUnlockAuthAttempt(
       app_manager_.get(), user_id,
       GetType() == TYPE_REGULAR ? EasyUnlockAuthAttempt::TYPE_UNLOCK
                                 : EasyUnlockAuthAttempt::TYPE_SIGNIN,
       callback));
   if (!auth_attempt_->Start())
     auth_attempt_.reset();
 }
 
@@ skipping 350 matching lines @@
 
   // TODO(tbarzic): Set check_private_key only if previous sign-in attempt
   // failed.
   EasyUnlockTpmKeyManagerFactory::GetInstance()->Get(profile_)
       ->PrepareTpmKey(true /* check_private_key */,
                       base::Closure());
 #endif  // defined(OS_CHROMEOS)
 
   tpm_key_checked_ = true;
 }