Expose network error

packages/google_sign_in/google_sign_in/android/src/main/java/io/flutter/plugins/googlesignin/GoogleSignInPlugin.java

@@ -173,6 +173,7 @@ public static final class Delegate implements IDelegate, PluginRegistry.Activity
     // These error codes must match with ones declared on iOS and Dart sides.
     private static final String ERROR_REASON_SIGN_IN_CANCELED = "sign_in_canceled";
     private static final String ERROR_REASON_SIGN_IN_REQUIRED = "sign_in_required";
+    private static final String ERROR_REASON_NETWORK_ERROR = "network_error";
     private static final String ERROR_REASON_SIGN_IN_FAILED = "sign_in_failed";
     private static final String ERROR_FAILURE_TO_RECOVER_AUTH = "failed_to_recover_auth";
     private static final String ERROR_USER_RECOVERABLE_AUTH = "user_recoverable_auth";
@@ -372,6 +373,8 @@ private String errorCodeForStatus(int statusCode) {
         return ERROR_REASON_SIGN_IN_CANCELED;
       } else if (statusCode == CommonStatusCodes.SIGN_IN_REQUIRED) {
         return ERROR_REASON_SIGN_IN_REQUIRED;
+      } else if (statusCode == CommonStatusCodes.NETWORK_ERROR) {
+        return ERROR_REASON_NETWORK_ERROR;
       } else {
         return ERROR_REASON_SIGN_IN_FAILED;
       }

packages/google_sign_in/google_sign_in/ios/Classes/FLTGoogleSignInPlugin.m

@@ -13,6 +13,7 @@
 // These error codes must match with ones declared on Android and Dart sides.
 static NSString *const kErrorReasonSignInRequired = @"sign_in_required";
 static NSString *const kErrorReasonSignInCanceled = @"sign_in_canceled";
+static NSString *const kErrorReasonNetworkError = @"network_error";
 static NSString *const kErrorReasonSignInFailed = @"sign_in_failed";
 
 static FlutterError *getFlutterError(NSError *error) {
@@ -21,6 +22,8 @@
     errorCode = kErrorReasonSignInRequired;
   } else if (error.code == kGIDSignInErrorCodeCanceled) {
     errorCode = kErrorReasonSignInCanceled;
+  } else if ([error.domain isEqualToString:NSURLErrorDomain]) {
+    errorCode = kErrorReasonNetworkError;
   } else {
     errorCode = kErrorReasonSignInFailed;
   }

packages/google_sign_in/google_sign_in/lib/google_sign_in.dart

@@ -194,6 +194,9 @@ class GoogleSignIn {
   /// user.
   static const String kSignInCanceledError = 'sign_in_canceled';
 
+  /// Error code indicating network error. Retrying should resolve the problem.
+  static const String kNetworkError = 'network_error';
+
   /// Error code indicating that attempt to sign in failed.
   static const String kSignInFailedError = 'sign_in_failed';
 
@@ -309,8 +312,9 @@ class GoogleSignIn {
   ///
   /// When [suppressErrors] is set to `false` and an error occurred during sign in
   /// returned Future completes with [PlatformException] whose `code` can be
-  /// either [kSignInRequiredError] (when there is no authenticated user) or
-  /// [kSignInFailedError] (when an unknown error occurred).
+  /// one of [kSignInRequiredError] (when there is no authenticated user) ,
+  /// [kNetworkError] (when a network error occurred) or [kSignInFailedError]
+  /// (when an unknown error occurred).
   Future<GoogleSignInAccount> signInSilently({
     bool suppressErrors = true,
   }) async {