Disable flakey test.

chrome/browser/chromeos/login/existing_user_controller_browsertest.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 <string>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
@@ skipping 525 matching lines @@
   EXPECT_TRUE(auto_login_timer()->IsRunning());
 
   // Unset the policy.
   SetAutoLoginPolicy("", 0);
   EXPECT_TRUE(!auto_login_account_id().is_valid());
   EXPECT_EQ(0, auto_login_delay());
   ASSERT_TRUE(auto_login_timer());
   EXPECT_FALSE(auto_login_timer()->IsRunning());
 }
 
+// Disable since the flake from this test makes it hard to track down other
+// problems on the bots.
+// See https://crbug.com/644205 or https://crbug.com/516015 .
 IN_PROC_BROWSER_TEST_F(ExistingUserControllerPublicSessionTest,
-                       AutoLoginNoDelay) {
+                       DISABLED_AutoLoginNoDelay) {
   // Set up mocks to check login success.
   UserContext user_context(user_manager::USER_TYPE_PUBLIC_ACCOUNT,
                            public_session_account_id_);
   user_context.SetUserIDHash(user_context.GetAccountId().GetUserEmail());
   ExpectSuccessfulLogin(user_context);
   existing_user_controller()->OnSigninScreenReady();
 
   // Start auto-login and wait for login tasks to complete.
   SetAutoLoginPolicy(kPublicSessionUserEmail, kAutoLoginNoDelay);
   content::RunAllPendingInMessageLoop();
@@ skipping 196 matching lines @@
                        PRE_TestLoadingPublicUsersFromLocalState) {
   // First run propagates public accounts and stores them in Local State.
 }
 
 IN_PROC_BROWSER_TEST_F(ExistingUserControllerPublicSessionTest,
                        TestLoadingPublicUsersFromLocalState) {
   // Second run loads list of public accounts from Local State.
 }
 
 }  // namespace chromeos