[signin] Support for empty accounts in MultiLoginParams in UPDATE mode

An empty account list in multilogin is not supported by Gaia.
In this CL we replace this by a Logout call,
which is the recommended way to do the same thing.

Change-Id: I61a3be41be35e27293efbe8cf7a9d3319a5a7d75
Reviewed-on: https://chromium-review.googlesource.com/c/1488874
Commit-Queue: David Roger <droger@chromium.org>
Reviewed-by: Boris Sazonov <bsazonov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#635537}

components/signin/core/browser/account_reconcilor.cc

@@ -126,13 +126,10 @@ bool AccountsNeedUpdate(
     const signin::MultiloginParameters& parameters,
     const std::vector<gaia::ListedAccount>& existing_accounts) {
   if (parameters.mode ==
-      gaia::MultiloginMode::MULTILOGIN_UPDATE_COOKIE_ACCOUNTS_ORDER) {
-    // In UPDATE mode accounts_to_send are guaranteed to be not empty.
-    DCHECK(!parameters.accounts_to_send.empty());
-    if (existing_accounts.empty())
-      return true;
-    // In UPDATE mode update is needed id syncing account is not first.
-    if (existing_accounts[0].id != parameters.accounts_to_send[0])
+          gaia::MultiloginMode::MULTILOGIN_UPDATE_COOKIE_ACCOUNTS_ORDER &&
+      !existing_accounts.empty() && !parameters.accounts_to_send.empty() &&
+      existing_accounts[0].id != parameters.accounts_to_send[0]) {
+    // In UPDATE mode update is needed if first accounts don't match.
     return true;
   }
   // Maybe some accounts in cookies are not valid and need refreshing.
@@ -502,6 +499,16 @@ void AccountReconcilor::FinishReconcileWithMultiloginEndpoint(
 
   DCHECK(is_reconcile_started_);
   if (AccountsNeedUpdate(parameters_for_multilogin, gaia_accounts)) {
+    if (parameters_for_multilogin.mode ==
+            gaia::MultiloginMode::MULTILOGIN_UPDATE_COOKIE_ACCOUNTS_ORDER &&
+        parameters_for_multilogin.accounts_to_send.empty()) {
+      // UPDATE mode does not support empty list of accounts, call logout
+      // instead.
+      PerformLogoutAllAccountsAction();
+      gaia_accounts.clear();
+      OnSetAccountsInCookieCompleted(GoogleServiceAuthError::AuthErrorNone());
+      DCHECK(!is_reconcile_started_);
+    } else {
       // Reconcilor has to do some calls to gaia. is_reconcile_started_ is true
       // and any StartReconcile() calls that are made in the meantime will be
       // aborted until OnSetAccountsInCookieCompleted is called and
@@ -509,7 +516,9 @@ void AccountReconcilor::FinishReconcileWithMultiloginEndpoint(
       set_accounts_in_progress_ = true;
       PerformSetCookiesAction(parameters_for_multilogin);
       DCHECK(is_reconcile_started_);
+    }
   } else {
+    // Nothing to do, accounts already match.
     OnSetAccountsInCookieCompleted(GoogleServiceAuthError::AuthErrorNone());
     DCHECK(!is_reconcile_started_);
   }

components/signin/core/browser/account_reconcilor.h

@@ -223,6 +223,7 @@ class AccountReconcilor : public KeyedService,
                            DelegateTimeoutIsNotCalled);
   FRIEND_TEST_ALL_PREFIXES(AccountReconcilorTest,
                            DelegateTimeoutIsNotCalledIfTimeoutIsNotReached);
+  FRIEND_TEST_ALL_PREFIXES(AccountReconcilorTest, MultiloginLogout);
 
   void set_timer_for_testing(std::unique_ptr<base::OneShotTimer> timer);
 

components/signin/core/browser/account_reconcilor_unittest.cc

@@ -2797,3 +2797,45 @@ TEST_F(AccountReconcilorTest, LockDestructionOrder) {
   DeleteReconcilor();
   // |lock| is destroyed after the reconcilor, this should not crash.
 }
+
+// Checks that multilogin with empty list of accounts in UPDATE mode is changed
+// into a Logout call.
+TEST_F(AccountReconcilorTest, MultiloginLogout) {
+  // Delegate implementation always returning UPDATE mode with no accounts.
+  class MultiloginLogoutDelegate : public signin::AccountReconcilorDelegate {
+    bool IsReconcileEnabled() const override { return true; }
+    bool IsAccountConsistencyEnforced() const override { return true; }
+    std::vector<std::string> GetChromeAccountsForReconcile(
+        const std::vector<std::string>& chrome_accounts,
+        const std::string& primary_account,
+        const std::vector<gaia::ListedAccount>& gaia_accounts,
+        const gaia::MultiloginMode mode) const override {
+      return {};
+    }
+    gaia::MultiloginMode CalculateModeForReconcile(
+        const std::vector<gaia::ListedAccount>& gaia_accounts,
+        const std::string primary_account,
+        bool first_execution,
+        bool primary_has_error) const override {
+      return gaia::MultiloginMode::MULTILOGIN_UPDATE_COOKIE_ACCOUNTS_ORDER;
+    }
+  };
+
+  base::test::ScopedFeatureList scoped_feature_list;
+  scoped_feature_list.InitAndEnableFeature(kUseMultiloginEndpoint);
+  MockAccountReconcilor* reconcilor =
+      GetMockReconcilor(std::make_unique<MultiloginLogoutDelegate>());
+  signin::SetListAccountsResponseOneAccount("user@gmail.com", "123456",
+                                            &test_url_loader_factory_);
+
+  // Logout call to Gaia.
+  EXPECT_CALL(*reconcilor, PerformLogoutAllAccountsAction());
+  // No multilogin call.
+  EXPECT_CALL(*reconcilor, PerformSetCookiesAction(testing::_)).Times(0);
+
+  reconcilor->StartReconcile();
+  ASSERT_TRUE(reconcilor->is_reconcile_started_);
+  base::RunLoop().RunUntilIdle();
+  EXPECT_FALSE(reconcilor->is_reconcile_started_);
+  ASSERT_EQ(signin_metrics::ACCOUNT_RECONCILOR_OK, reconcilor->GetState());
+}