code review comments

Author: morganchen12

FirebaseGoogleAuthUI/Sources/FUIGoogleAuth.m

@@ -101,7 +101,7 @@ - (instancetype)initWithScopes:(NSArray *)scopes {
 #pragma clang diagnostic pop
 
 - (GIDSignIn *)googleSignIn {
-  return [GIDSignIn sharedInstance];
+  return GIDSignIn.sharedInstance;
 }
 
 - (NSString *)clientID {
@@ -247,7 +247,7 @@ - (void)requestScopesWithPresentingViewController:(UIViewController *)presenting
                                  FIRAuthResultCallback result,
                                  NSDictionary<NSString *,id> *userInfo) {
       if (completion != nil) {
-        completion(credential, error, result, nil);
+        completion(credential, error, result, userInfo);
       }
     }];
   }];

FirebaseGoogleAuthUI/Sources/Public/FirebaseGoogleAuthUI/FUIGoogleAuth.h

@@ -89,7 +89,7 @@ __attribute__((deprecated("Instead use initWithAuthUI:")));
 - (instancetype)initWithScopes:(NSArray <NSString *> *)scopes
 __attribute__((deprecated("Instead use initWithAuthUI:permissions:"))) NS_DESIGNATED_INITIALIZER;
 
-/** @fn initWithAuthUI:scopes:
+/** @fn requestScopesWithPresentingViewController:completion:
     @brief Requests the scopes in the `scopes` array.
  */
 - (void)requestScopesWithPresentingViewController:(UIViewController *)presentingViewController