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

components/signin/core/browser/signin_investigator_unittest.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 <string>
 
 #include "base/test/histogram_tester.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/testing_pref_service.h"
 #include "components/signin/core/browser/signin_investigator.h"
@@ skipping 24 matching lines @@
   TestingPrefServiceSimple prefs_;
 };
 }  // namespace
 
 class SigninInvestigatorTest : public testing::Test {
  protected:
   void AssertAccountEquality(const std::string& email,
                              const std::string& id,
                              bool equals_expectated,
                              AccountEquality histogram_expected) {
-    base::HistogramTester histogram_tester;
     FakeProvider provider(email, id);
     SigninInvestigator investigator(kSameEmail, kSameId, &provider);
-    bool equals_actual = investigator.AreAccountsEqualWithFallback();
+    AssertAccountEquality(&investigator, equals_expectated, histogram_expected);
+  }
+
+  void AssertAccountEquality(SigninInvestigator* investigator,
+                             bool equals_expectated,
+                             AccountEquality histogram_expected) {
+    base::HistogramTester histogram_tester;
+    bool equals_actual = investigator->AreAccountsEqualWithFallback();
     ASSERT_EQ(equals_expectated, equals_actual);
     histogram_tester.ExpectUniqueSample(
         "Signin.AccountEquality", static_cast<int>(histogram_expected), 1);
   }
 
   void AssertInvestigatedScenario(const std::string& email,
                                   const std::string& id,
                                   InvestigatedScenario expected) {
     base::HistogramTester histogram_tester;
     FakeProvider provider(email, id);
@@ skipping 27 matching lines @@
 TEST_F(SigninInvestigatorTest, EqualitySameEmailFallback) {
   AssertAccountEquality(kSameEmail, kEmptyId, true,
                         AccountEquality::EMAIL_FALLBACK);
 }
 
 TEST_F(SigninInvestigatorTest, EqualityDifferentEmailFallback) {
   AssertAccountEquality(kDifferentEmail, kEmptyId, false,
                         AccountEquality::EMAIL_FALLBACK);
 }
 
+TEST_F(SigninInvestigatorTest, EqualitySameEmailFallbackEmptyCurrentId) {
+  FakeProvider provider(kSameEmail, kDifferentId);
+  SigninInvestigator investigator(kSameEmail, kEmptyId, &provider);
+  AssertAccountEquality(&investigator, true, AccountEquality::EMAIL_FALLBACK);
+}
+
+TEST_F(SigninInvestigatorTest, EqualityDifferentEmailFallbackEmptyCurrentId) {
+  FakeProvider provider(kDifferentId, kDifferentId);
+  SigninInvestigator investigator(kSameEmail, kEmptyId, &provider);
+  AssertAccountEquality(&investigator, false, AccountEquality::EMAIL_FALLBACK);
+}
+
 TEST_F(SigninInvestigatorTest, InvestigateSameAccount) {
   AssertInvestigatedScenario(kSameEmail, kSameId,
                              InvestigatedScenario::SAME_ACCOUNT);
 }
 
 TEST_F(SigninInvestigatorTest, InvestigateUpgrade) {
   AssertInvestigatedScenario("", "", InvestigatedScenario::UPGRADE_LOW_RISK);
 }
 
 TEST_F(SigninInvestigatorTest, InvestigateDifferentAccount) {
   AssertInvestigatedScenario(kDifferentEmail, kDifferentId,
                              InvestigatedScenario::DIFFERENT_ACCOUNT);
 }