[Sync] Removed a DCHECK in SigninInvestigator for a valid scenario.

components/signin/core/browser/signin_investigator.cc

 // Copyright 2015 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 "components/signin/core/browser/signin_investigator.h"
 
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "components/signin/core/browser/signin_metrics.h"
 #include "components/signin/core/common/signin_pref_names.h"
@@ skipping 10 matching lines @@
 }
 }  // namespace
 
 SigninInvestigator::SigninInvestigator(const std::string& current_email,
                                        const std::string& current_id,
                                        DependencyProvider* provider)
     : current_email_(current_email),
       current_id_(current_id),
       provider_(provider) {
   DCHECK(!current_email_.empty());
-  DCHECK(!current_id_.empty());
+  DCHECK(provider);
 }
 
 SigninInvestigator::~SigninInvestigator() {}
 
 bool SigninInvestigator::AreAccountsEqualWithFallback() {
   const std::string last_id =
       provider_->GetPrefs()->GetString(prefs::kGoogleServicesLastAccountId);
   bool same_email = gaia::AreEmailsSame(
       current_email_,
       provider_->GetPrefs()->GetString(prefs::kGoogleServicesLastUsername));
@@ skipping 29 matching lines @@
   }
 
   LogSigninScenario(scenario);
   return scenario;
 }
 
 bool SigninInvestigator::IsUpgradeHighRisk() {
   // TODO(skym): Add logic to make this decision, crbug.com/572754.
   return false;
 }