[webview_flutter] add public documentation. (#3114)

diff --git a/packages/webview_flutter/CHANGELOG.md b/packages/webview_flutter/CHANGELOG.md
index f327245..56c4dd9 100644
--- a/packages/webview_flutter/CHANGELOG.md
+++ b/packages/webview_flutter/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 1.0.1
+
+* Add documentation for `WebViewPlatformCreatedCallback`.
+
 ## 1.0.0 - Out of developer preview 🎉.
 
 * Bumped the minimal Flutter SDK to 1.22 where platform views are out of developer preview, and
diff --git a/packages/webview_flutter/lib/platform_interface.dart b/packages/webview_flutter/lib/platform_interface.dart
index 0f848ec..6c991b1 100644
--- a/packages/webview_flutter/lib/platform_interface.dart
+++ b/packages/webview_flutter/lib/platform_interface.dart
@@ -471,6 +471,9 @@
   }
 }
 
+/// Signature for callbacks reporting that a [WebViewPlatformController] was created.
+///
+/// See also the `onWebViewPlatformCreated` argument for [WebViewPlatform.build].
 typedef WebViewPlatformCreatedCallback = void Function(
     WebViewPlatformController webViewPlatformController);
 
diff --git a/packages/webview_flutter/pubspec.yaml b/packages/webview_flutter/pubspec.yaml
index aa9c606..a38d328 100644
--- a/packages/webview_flutter/pubspec.yaml
+++ b/packages/webview_flutter/pubspec.yaml
@@ -1,6 +1,6 @@
 name: webview_flutter
 description: A Flutter plugin that provides a WebView widget on Android and iOS.
-version: 1.0.0
+version: 1.0.1
 homepage: https://github.com/flutter/plugins/tree/master/packages/webview_flutter
 
 environment: