[google_sign_in] Add a platform interface method to clear auth tokens (#9929)

Platform interface portion of #9846

Part of flutter/flutter#173924

## Pre-Review Checklist

[^1]: Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling.

Author: stuartmorgan-g

packages/google_sign_in/google_sign_in_platform_interface/CHANGELOG.md

@@ -1,5 +1,7 @@
-## NEXT
+## 3.1.0
 
+* Adds a `clearAuthorizationToken` method to remove an access token from the
+  cache.
 * Updates minimum supported SDK version to Flutter 3.29/Dart 3.7.
 
 ## 3.0.0

packages/google_sign_in/google_sign_in_platform_interface/lib/google_sign_in_platform_interface.dart

@@ -98,6 +98,13 @@ abstract class GoogleSignInPlatform extends PlatformInterface {
     ServerAuthorizationTokensForScopesParameters params,
   );
 
+  /// Clears any token cache for the given access token.
+  Future<void> clearAuthorizationToken(ClearAuthorizationTokenParams params) {
+    throw UnimplementedError(
+      'clearAuthorizationToken() has not been implemented.',
+    );
+  }
+
   /// Signs out previously signed in accounts.
   Future<void> signOut(SignOutParams params);
 
@@ -168,6 +175,11 @@ class _PlaceholderImplementation extends GoogleSignInPlatform {
     throw UnimplementedError();
   }
 
+  @override
+  Future<void> clearAuthorizationToken(ClearAuthorizationTokenParams params) {
+    throw UnimplementedError();
+  }
+
   @override
   Future<void> signOut(SignOutParams params) {
     throw UnimplementedError();

packages/google_sign_in/google_sign_in_platform_interface/lib/src/types.dart

@@ -363,6 +363,29 @@ class AuthenticationResults {
   final AuthenticationTokenData authenticationTokens;
 }
 
+/// Parameters for the clearAuthorizationToken method.
+@immutable
+class ClearAuthorizationTokenParams {
+  /// Creates new parameters for clearAuthorizationToken with the given
+  /// [accessToken]
+  const ClearAuthorizationTokenParams({required this.accessToken});
+
+  /// The OAuth2 access token to clear.
+  final String accessToken;
+
+  @override
+  int get hashCode => accessToken.hashCode;
+
+  @override
+  bool operator ==(Object other) {
+    if (other.runtimeType != runtimeType) {
+      return false;
+    }
+    return other is ClearAuthorizationTokenParams &&
+        other.accessToken == accessToken;
+  }
+}
+
 /// Parameters for the signOut method.
 @immutable
 class SignOutParams {

packages/google_sign_in/google_sign_in_platform_interface/pubspec.yaml

@@ -4,7 +4,7 @@ repository: https://github.com/flutter/packages/tree/main/packages/google_sign_i
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+google_sign_in%22
 # NOTE: We strongly prefer non-breaking changes, even at the expense of a
 # less-clean API. See https://flutter.dev/go/platform-interface-breaking-changes
-version: 3.0.0
+version: 3.1.0
 
 environment:
   sdk: ^3.7.0

packages/google_sign_in/google_sign_in_platform_interface/test/google_sign_in_platform_interface_test.dart

@@ -37,6 +37,21 @@ void main() {
       // this behavior, which could be implemented in the subclass.
       expect(ExtendsGoogleSignInPlatform().authenticationEvents, null);
     });
+
+    test(
+      'Default implementation of clearAuthorizationToken throws unimplemented error',
+      () {
+        final ExtendsGoogleSignInPlatform platform =
+            ExtendsGoogleSignInPlatform();
+
+        expect(
+          () => platform.clearAuthorizationToken(
+            const ClearAuthorizationTokenParams(accessToken: 'someToken'),
+          ),
+          throwsUnimplementedError,
+        );
+      },
+    );
   });
 
   group('GoogleSignInUserData', () {