Description

This PR adds a unified Permission Handler API for intercepting webview permission requests across WebView2, WKWebView, WebKitGTK, and Android.

The API lets applications decide how to handle permission requests at runtime by returning Allow, Deny, or Default from a new WebViewBuilder::with_permission_handler callback.

Default falls back to the platform or browser default behavior instead of forcing an explicit prompt. This keeps the API portable across backends where prompt/default handling is exposed differently.

Key Changes

• Added WebViewBuilder::with_permission_handler.
• Added PermissionKind for webview permission categories such as camera, microphone, geolocation, notifications, display capture, MIDI, local fonts, file system access, autoplay, and more.
• Added PermissionResponse with Allow, Deny, and Default.
• Added a permission_handler example using permission.site.

Platform Implementations

• Windows (WebView2)

  • Handles WebView2 PermissionRequested events.
  • Maps WebView2 permission kinds to PermissionKind.
  • Applies Allow and Deny; Default leaves WebView2 default handling in place.

• macOS / iOS (WKWebView)

  • Handles requestMediaCapturePermission.
  • Maps camera and microphone capture requests to PermissionKind.
  • Maps Default to WebKit's prompt/default permission flow.
  • Handles combined CameraAndMicrophone requests by checking camera and microphone separately, with deny taking precedence.

• Linux (WebKitGTK)

  • Handles the permission-request signal.
  • Supports geolocation, notifications, pointer lock, camera, microphone, and display capture where available.
  • Uses is_for_display_device() with the v2_42 feature and falls back to display-capture detection for older WebKitGTK versions.
  • Leaves the request unhandled for Default, so WebKitGTK can apply its default behavior.

• Android

  • Handles WebChromeClient.onPermissionRequest and geolocation permission prompts through JNI.
  • Supports camera, microphone, protected media, MIDI, and geolocation requests.
  • Scopes permission handlers per WebView so multi-webview apps route requests to the correct handler.
  • Deny rejects the Android request; Allow and Default continue the normal Android runtime permission flow.
  • Android runtime permissions may still trigger native OS prompts before access is granted.

Example

cargo run --example permission_handler