[google_sign_in] Update (web) example app. (#5634)

## Changes

**google_sign_in:**

* Updates web bootstrap following [Flutter Web initialization docs](https://docs.flutter.dev/platform-integration/web/initialization#skipping-this-step).
* Uses the recent [`web_only` library](https://pub.dev/documentation/google_sign_in_web/0.12.3/web_only/web_only-library.html) to `renderButton`.
* Updates dependencies so it can compile with `--wasm`.

(opportunistic weekend commit) **google_identity_services_web:**

* Adds missing `CredentialSelectBy.fedcm_auto` enum value.
* Bump patch version + changelog.

## Issues

* Fixes https://github.com/flutter/flutter/issues/139852
* Missing bit of https://github.com/flutter/flutter/issues/138202

## Testing

* Deployed to: https://dit-gis-test.web.app

packages/google_identity_services_web/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.3.0+2
+
+* Adds `fedcm_auto` to `CredentialSelectBy` enum.
+* Adds `unknown_reason` to all `Moment*Reason` enums.
+
 ## 0.3.0+1
 
 * Corrects 0.3.0 changelog entry about the minimum Flutter/Dart dependencies.

packages/google_identity_services_web/lib/src/js_interop/shared.dart

@@ -118,7 +118,10 @@ enum MomentSkippedReason {
   tap_outside('tap_outside'),
 
   /// issuing_failed
-  issuing_failed('issuing_failed');
+  issuing_failed('issuing_failed'),
+
+  /// Unknown reason
+  unknown_reason('unknown_reason');
 
   ///
   const MomentSkippedReason(String reason) : _reason = reason;
@@ -137,7 +140,10 @@ enum MomentDismissedReason {
   cancel_called('cancel_called'),
 
   /// flow_restarted
-  flow_restarted('flow_restarted');
+  flow_restarted('flow_restarted'),
+
+  /// Unknown reason
+  unknown_reason('unknown_reason');
 
   ///
   const MomentDismissedReason(String reason) : _reason = reason;
@@ -207,7 +213,10 @@ enum CredentialSelectBy {
   btn_confirm_add_session('btn_confirm_add_session'),
 
   /// A user with an existing session used the browser's "FedCM" flow.
-  fedcm('fedcm');
+  fedcm('fedcm'),
+
+  /// A fedcm authentication without user intervention.
+  fedcm_auto('fedcm_auto');
 
   ///
   const CredentialSelectBy(String selectBy) : _selectBy = selectBy;

packages/google_identity_services_web/pubspec.yaml

@@ -2,7 +2,7 @@ name: google_identity_services_web
 description: A Dart JS-interop layer for Google Identity Services. Google's new sign-in SDK for Web that supports multiple types of credentials.
 repository: https://github.com/flutter/packages/tree/main/packages/google_identity_services_web
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+google_identiy_services_web%22
-version: 0.3.0+1
+version: 0.3.0+2
 
 environment:
   sdk: ">=3.2.0 <4.0.0"

packages/google_sign_in/google_sign_in/example/lib/src/sign_in_button/web.dart

@@ -3,13 +3,11 @@
 // found in the LICENSE file.
 
 import 'package:flutter/material.dart';
-import 'package:google_sign_in_platform_interface/google_sign_in_platform_interface.dart';
-import 'package:google_sign_in_web/google_sign_in_web.dart' as web;
+import 'package:google_sign_in_web/web_only.dart' as web;
 
 import 'stub.dart';
 
 /// Renders a web-only SIGN IN button.
 Widget buildSignInButton({HandleSignInFn? onPressed}) {
-  return (GoogleSignInPlatform.instance as web.GoogleSignInPlugin)
-      .renderButton();
+  return web.renderButton();
 }

packages/google_sign_in/google_sign_in/example/pubspec.yaml

@@ -3,8 +3,8 @@ description: Example of Google Sign-In plugin.
 publish_to: none
 
 environment:
-  sdk: ">=3.0.0 <4.0.0"
-  flutter: ">=3.10.0"
+  sdk: ^3.2.0
+  flutter: ">=3.16.0"
 
 dependencies:
   flutter:
@@ -16,8 +16,7 @@ dependencies:
     # The example app is bundled with the plugin so we use a path dependency on
     # the parent directory to use the current plugin's version.
     path: ../
-  google_sign_in_platform_interface: ^2.4.0
-  google_sign_in_web: ^0.12.0
+  google_sign_in_web: ^0.12.3
   http: ">=0.13.0 <2.0.0"
 
 dev_dependencies:

packages/google_sign_in/google_sign_in/example/web/index.html

@@ -7,8 +7,17 @@ found in the LICENSE file. -->
   <meta charset="UTF-8">
   <meta name="google-signin-client_id" content="your-client_id.apps.googleusercontent.com">
   <title>Google Sign-in Example</title>
+  <script src="flutter.js" defer></script>
 </head>
 <body>
-  <script src="main.dart.js" type="application/javascript"></script>
+  <script>
+    window.addEventListener('load', function(ev) {
+      _flutter.loader.loadEntrypoint({
+        onEntrypointLoaded: function(engineInitializer) {
+          engineInitializer.autoStart();
+        }
+      });
+    });
+  </script>
 </body>
 </html>