[iOS] Fix broken tests due to missing completion in fake ViewController.

AddAccountSigninManagerTests were failing due to a missing run
completion. Remove intermediary method that causes this failure.

Bug: 1078815
Change-Id: I1766e593927cd40be318cf66bb67d11f5ed47006
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2264057
Commit-Queue: Jérôme Lebel <jlebel@chromium.org>
Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782928}

ios/chrome/browser/ui/authentication/signin/signin_coordinator_egtest.mm

@@ -496,8 +496,7 @@ void ChooseImportOrKeepDataSepareteDialog(id<GREYMatcher> choiceButtonMatcher) {
   [SigninEarlGreyUtils
       waitForMatcher:grey_accessibilityID(kFakeAddAccountViewIdentifier)];
   // Close the SSO view controller.
-  id<GREYMatcher> matcher =
-      grey_allOf(chrome_test_util::ButtonWithAccessibilityLabel(@"Cancel"),
+  id<GREYMatcher> matcher = grey_allOf(ButtonWithAccessibilityLabel(@"Cancel"),
                                        grey_sufficientlyVisible(), nil);
   [[EarlGrey selectElementWithMatcher:matcher] performAction:grey_tap()];
   // Make sure the SSO view controller is fully removed before ending the test.
@@ -515,11 +514,14 @@ void ChooseImportOrKeepDataSepareteDialog(id<GREYMatcher> choiceButtonMatcher) {
   [SigninEarlGreyUI tapAddAccountButton];
 
   [self assertFakeSSOScreenIsVisible];
+
   // Close sign-in screen and Settings.
   [[EarlGrey selectElementWithMatcher:
                  ButtonWithAccessibilityLabelId(
                      IDS_IOS_ACCOUNT_CONSISTENCY_SETUP_SKIP_BUTTON)]
       performAction:grey_tap()];
+  [[EarlGrey selectElementWithMatcher:SettingsDoneButton()]
+      performAction:grey_tap()];
   [[GREYUIThreadExecutor sharedInstance] drainUntilIdle];
 }
 

ios/public/provider/chrome/browser/signin/fake_chrome_identity_interaction_manager.mm

@@ -174,7 +174,7 @@
     [self runCompletionCallbackWithError:error];
     return;
   }
-  [self.delegate interactionManager:self
+  [_viewController
       dismissViewControllerAnimated:animated
                          completion:^{
                            [self runCompletionCallbackWithError:error];