[iOS] Do not allow simultaneous sign-in operations.

The SignOut operation with Chrome data clearing does not have the
proper conditionals in place to ensure that a subsequent operation
cannot occur while sign-out is in progress.

We suspect this causes a crash on sign-out / sign-in to switch accounts
since the navigation controller that AccountsTableViewController
attempts to perform an operation on may no longer exist.

https://crash.corp.google.com/browse?q=product_name%3D%27Chrome_iOS%27+AND+expanded_custom_data.ChromeCrashProto.channel%3D%27%27+AND+expanded_custom_data.ChromeCrashProto.magic_signature_1.name%3D%27%5BHang%5Dweb%3A%3AWebSubThread%3A%3AIOThreadRun%27+AND+%28EXISTS+%28SELECT+1+FROM+UNNEST%28productdata%29+WHERE+key%3D%27breadcrumbs0%27%29+OR+EXISTS+%28SELECT+1+FROM+UNNEST%28productdata%29+WHERE+key%3D%27breadcrumbs%27%29%29&stbtiq=&reportid=&index=0

Bug: 1108310
Change-Id: I66d1852d1071d7acea243005bfabc7797af14dd3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2408754Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Nohemi Fernandez <fernandex@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806613}

ios/chrome/browser/ui/settings/google_services/accounts_table_egtest.mm

@@ -256,6 +256,23 @@ id<GREYMatcher> NoBookmarksLabel() {
       assertWithMatcher:grey_notNil()];
 }
 
+// Tests that given two accounts A and B that are available on the device -
+// signing in and out from account A, then signing in to account B, properly
+// identifies the user with account B.
+- (void)testSwitchingAccountsWithClearedData {
+  FakeChromeIdentity* fakeIdentity1 = [SigninEarlGrey fakeIdentity1];
+  FakeChromeIdentity* fakeIdentity2 = [SigninEarlGrey fakeIdentity2];
+  [SigninEarlGrey addFakeIdentity:fakeIdentity1];
+  [SigninEarlGrey addFakeIdentity:fakeIdentity2];
+
+  [SigninEarlGreyUI signinWithFakeIdentity:fakeIdentity1];
+  [SigninEarlGrey verifySignedInWithFakeIdentity:fakeIdentity1];
+  [SigninEarlGreyUI signOutAndClearDataFromDevice];
+
+  [SigninEarlGreyUI signinWithFakeIdentity:fakeIdentity2];
+  [SigninEarlGrey verifySignedInWithFakeIdentity:fakeIdentity2];
+}
+
 // Tests that the user isn't signed out and the UI is correct when the
 // disconnect is cancelled in the Account Settings screen.
 #if !TARGET_IPHONE_SIMULATOR

ios/chrome/browser/ui/settings/google_services/accounts_table_view_controller.mm

@@ -498,6 +498,12 @@ typedef NS_ENUM(NSInteger, ItemType) {
 
 - (void)showSignOutWithClearData:(BOOL)forceClearData
                         itemView:(UIView*)itemView {
+  if (_authenticationOperationInProgress || [_alertCoordinator isVisible] ||
+      self != [self.navigationController topViewController]) {
+    // An action is already in progress, ignore user's request.
+    return;
+  }
+
   NSString* alertMessage = nil;
   NSString* signOutTitle = nil;
   UIAlertActionStyle actionStyle = UIAlertActionStyleDefault;
@@ -537,51 +543,6 @@ typedef NS_ENUM(NSInteger, ItemType) {
   [_alertCoordinator start];
 }
 
-- (void)showSignOut {
-  if (_authenticationOperationInProgress || [_alertCoordinator isVisible] ||
-      self != [self.navigationController topViewController]) {
-    // An action is already in progress, ignore user's request.
-    return;
-  }
-
-  NSString* title = nil;
-  NSString* message = nil;
-  NSString* continueButtonTitle = nil;
-
-  if ([self authService] -> IsAuthenticatedIdentityManaged()) {
-    title =
-        l10n_util::GetNSString(IDS_IOS_MANAGED_DISCONNECT_DIALOG_TITLE_UNITY);
-    message = l10n_util::GetNSStringF(
-        IDS_IOS_MANAGED_DISCONNECT_DIALOG_INFO_UNITY, self.hostedDomain);
-    continueButtonTitle =
-        l10n_util::GetNSString(IDS_IOS_MANAGED_DISCONNECT_DIALOG_ACCEPT_UNITY);
-  } else {
-    title = l10n_util::GetNSString(IDS_IOS_DISCONNECT_DIALOG_TITLE_UNITY);
-    message =
-        l10n_util::GetNSString(IDS_IOS_DISCONNECT_DIALOG_INFO_MOBILE_UNITY);
-    continueButtonTitle = l10n_util::GetNSString(
-        IDS_IOS_DISCONNECT_DIALOG_CONTINUE_BUTTON_MOBILE);
-  }
-
-  _alertCoordinator =
-      [[AlertCoordinator alloc] initWithBaseViewController:self
-                                                   browser:_browser
-                                                     title:title
-                                                   message:message];
-
-  __weak AccountsTableViewController* weakSelf = self;
-  [_alertCoordinator addItemWithTitle:l10n_util::GetNSString(IDS_CANCEL)
-                               action:nil
-                                style:UIAlertActionStyleCancel];
-  [_alertCoordinator addItemWithTitle:continueButtonTitle
-                               action:^{
-                                 [weakSelf handleSignOutWithForceClearData:NO];
-                               }
-                                style:UIAlertActionStyleDefault];
-
-  [_alertCoordinator start];
-}
-
 - (void)handleSignOutWithForceClearData:(BOOL)forceClearData {
   AuthenticationService* authService = [self authService];
   if (authService->IsAuthenticated()) {
@@ -590,10 +551,7 @@ typedef NS_ENUM(NSInteger, ItemType) {
     authService->SignOut(
         signin_metrics::USER_CLICKED_SIGNOUT_SETTINGS, forceClearData, ^{
           [self allowUserInteraction];
-          _authenticationOperationInProgress = NO;
-          [base::mac::ObjCCastStrict<SettingsNavigationController>(
-              self.navigationController)
-              popViewControllerOrCloseSettingsAnimated:YES];
+          [self handleAuthenticationOperationDidFinish];
         });
     // Get UMA metrics on the usage of different options for signout available
     // for users with non-managed accounts.