Clean up pass on DiceTurnSyncOnHelper code

This is a follow up CL to [1], that addresses post-land feedback from blundell@.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/1387393/6#message-5b6d62524d8612f8d9b11bd7500af41f4f10cc76

BUG=890811,890812

Change-Id: Ie01be10511872dca5b053d20386559d2975e4bff
Reviewed-on: https://chromium-review.googlesource.com/c/1391688Reviewed-by: Colin Blundell <blundell@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Cr-Commit-Position: refs/heads/master@{#619771}

chrome/browser/ui/webui/signin/dice_turn_sync_on_helper.cc

@@ -442,7 +442,6 @@ void DiceTurnSyncOnHelper::OnNewProfileTokensLoaded(Profile* new_profile) {
 void DiceTurnSyncOnHelper::SigninAndShowSyncConfirmationUI() {
   // Signin.
   auto* primary_account_mutator = identity_manager_->GetPrimaryAccountMutator();
-  DCHECK(primary_account_mutator);
   primary_account_mutator->SetPrimaryAccount(account_info_.account_id);
   signin_metrics::LogSigninAccessPointCompleted(signin_access_point_,
                                                 signin_promo_action_);

chrome/browser/ui/webui/signin/dice_turn_sync_on_helper.h

@@ -30,8 +30,8 @@ class SyncService;
 class SyncSetupInProgressHandle;
 }
 
-// Handles details of signing the user in with IdentityManager and turning on
-// sync for an account that is already present in the token service.
+// Handles details of setting the primary account with IdentityManager and
+// turning on sync for an account for which there is already a refresh token.
 class DiceTurnSyncOnHelper : public SyncStartupTracker::Observer {
  public:
   // Behavior when the signin is aborted (by an error or cancelled by the user).

chrome/browser/ui/webui/signin/dice_turn_sync_on_helper_unittest.cc

@@ -175,14 +175,6 @@ std::unique_ptr<TestingProfile> BuildTestingProfile(
     const base::FilePath& path,
     Profile::Delegate* delegate) {
   TestingProfile::Builder profile_builder;
-
-  TestingProfile::TestingFactories testing_factories =
-      IdentityTestEnvironmentProfileAdaptor::
-          GetIdentityTestEnvironmentFactories();
-  for (auto& testing_factory : testing_factories) {
-    profile_builder.AddTestingFactory(testing_factory.first,
-                                      testing_factory.second);
-  }
   profile_builder.AddTestingFactory(
       ChromeSigninClientFactory::GetInstance(),
       base::BindRepeating(&signin::BuildTestSigninClient));
@@ -194,7 +186,8 @@ std::unique_ptr<TestingProfile> BuildTestingProfile(
       base::BindRepeating(&FakeUserPolicySigninService::Build));
   profile_builder.SetDelegate(delegate);
   profile_builder.SetPath(path);
-  return profile_builder.Build();
+  return IdentityTestEnvironmentProfileAdaptor::
+      CreateProfileForIdentityTestEnvironment(profile_builder);
 }
 
 }  // namespace
@@ -808,7 +801,7 @@ TEST_F(DiceTurnSyncOnHelperTest,
   DiceTurnSyncOnHelper* dice_sync_starter = CreateDiceTurnOnSyncHelper(
       DiceTurnSyncOnHelper::SigninAbortedMode::REMOVE_ACCOUNT);
 
-  // Check that the account was set in the sign-in manager, but the sync
+  // Check that the primary account was set with IdentityManager, but the sync
   // confirmation dialog was not yet shown.
   EXPECT_TRUE(identity_manager()->HasAccountWithRefreshToken(account_id()));
   EXPECT_EQ(account_id(), identity_manager()->GetPrimaryAccountId());