Fix "unused variable" warnings.

chrome/browser/signin/signin_status_metrics_provider_chromeos_unittest.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/signin_status_metrics_provider_chromeos.h"
 
 #include <string>
 
 #include "base/files/file_path.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 TEST(SigninStatusMetricsProviderChromeOS, ComputeSigninStatusToUpload) {
-  SigninStatusMetricsProviderChromeOS metrics_provider =
-      SigninStatusMetricsProviderChromeOS();
+  SigninStatusMetricsProviderChromeOS metrics_provider;
 
   SigninStatusMetricsProviderBase::SigninStatus status_to_upload =
       metrics_provider.ComputeSigninStatusToUpload(
           SigninStatusMetricsProviderBase::ALL_PROFILES_SIGNED_IN, true);
   EXPECT_EQ(SigninStatusMetricsProviderBase::ALL_PROFILES_SIGNED_IN,
             status_to_upload);
 
   status_to_upload = metrics_provider.ComputeSigninStatusToUpload(
       SigninStatusMetricsProviderBase::ALL_PROFILES_NOT_SIGNED_IN, false);
   EXPECT_EQ(SigninStatusMetricsProviderBase::ALL_PROFILES_NOT_SIGNED_IN,
             status_to_upload);
 
   status_to_upload = metrics_provider.ComputeSigninStatusToUpload(
       SigninStatusMetricsProviderBase::ALL_PROFILES_NOT_SIGNED_IN, true);
   EXPECT_EQ(SigninStatusMetricsProviderBase::MIXED_SIGNIN_STATUS,
             status_to_upload);
 
   status_to_upload = metrics_provider.ComputeSigninStatusToUpload(
       SigninStatusMetricsProviderBase::ALL_PROFILES_SIGNED_IN, false);
   EXPECT_EQ(SigninStatusMetricsProviderBase::ERROR_GETTING_SIGNIN_STATUS,
             status_to_upload);
 }