Make sure the first valid auth domain is retrieved (#3493)

Author: renkelvin

Example/Auth/Sample/MainViewController+OAuth.m

@@ -29,18 +29,18 @@ - (StaticContentTableViewSection *)oAuthSection {
   return [StaticContentTableViewSection sectionWithTitle:@"OAuth" cells:@[
     [StaticContentTableViewCell cellWithTitle:@"Sign in with Google"
                                        action:^{ [weakSelf signInGoogleHeadfulLite]; }],
-    [StaticContentTableViewCell cellWithTitle:@"Sign In with Twitter (headful-lite)"
+    [StaticContentTableViewCell cellWithTitle:@"Sign in with Twitter"
                                        action:^{ [weakSelf signInTwitterHeadfulLite]; }],
-    [StaticContentTableViewCell cellWithTitle:@"Sign In with Linkedin"
-                                       action:^{ [weakSelf signInLinkedinHeadfulLite]; }],
-    [StaticContentTableViewCell cellWithTitle:@"Sign In with GitHub (access token)"
-                                       action:^{ [weakSelf signInWithGitHub]; }],
-    [StaticContentTableViewCell cellWithTitle:@"Sign In with GitHub (headful-lite)"
+    [StaticContentTableViewCell cellWithTitle:@"Sign in with GitHub"
                                        action:^{ [weakSelf signInGitHubHeadfulLite]; }],
+    [StaticContentTableViewCell cellWithTitle:@"Sign in with GitHub (Access token)"
+                                       action:^{ [weakSelf signInWithGitHub]; }],
     [StaticContentTableViewCell cellWithTitle:@"Sign in with Microsoft"
                                        action:^{ [weakSelf signInMicrosoftHeadfulLite]; }],
-    [StaticContentTableViewCell cellWithTitle:@"Sign In with Yahoo"
+    [StaticContentTableViewCell cellWithTitle:@"Sign in with Yahoo"
                                        action:^{ [weakSelf signInYahooHeadfulLite]; }],
+    [StaticContentTableViewCell cellWithTitle:@"Sign in with Linkedin"
+                                       action:^{ [weakSelf signInLinkedinHeadfulLite]; }],
     ]];
 }
 

Firebase/Auth/Source/Utilities/FIRAuthWebUtils.m

@@ -96,6 +96,9 @@ + (void)fetchAuthDomainWithRequestConfiguration:(FIRAuthRequestConfiguration *)r
       completion(nil, error);
       return;
     }
+    // Look up an authorized domain ends with one of the supportedAuthDomains.
+    // The sequence of supportedAuthDomains matters. ("firebaseapp.com", "web.app")
+    // The searching ends once the first valid suportedAuthDomain is found.
     NSString *authDomain;
     for (NSString *domain in response.authorizedDomains) {
       for (NSString *suportedAuthDomain in [self supportedAuthDomains]) {
@@ -107,6 +110,9 @@ + (void)fetchAuthDomainWithRequestConfiguration:(FIRAuthRequestConfiguration *)r
           }
         }
       }
+      if (authDomain != nil) {
+        break;
+      }
     }
     if (!authDomain.length) {
       completion(nil, [FIRAuthErrorUtils unexpectedErrorResponseWithDeserializedResponse:response]);