The WebView team supports both the Android and Chromium Privacy Sandbox initiatives. Below please find details of work related to these efforts:
The WebView SDK Sandbox Test App and SDK are a standalone application and sdk in chromium for testing WebView in a privacy sandbox environment.
Ensure you are testing with a device/emulator that supports Privacy Sandbox (https://developer.android.com/design-for-safety/privacy-sandbox/download#device). You will need to add the following to your GN args:
target_os = "android"
$ autoninja -C out/Default sdk_sandbox
$ out/Default/bin/sdk_sandbox_webview_sdk install
$ out/Default/bin/sdk_sandbox_webview_client install
Open the app via its launch icon in the menu.
You will first need to click the “Load SDK” button to load the SDK that will return the WebView. Next click the “Load Surface Package” button to load the WebView in the space below. The WebView will default to loading the Google home page, you can use the url bar to navigate to your desired test page. You can also test unloading the SDK by clicking the “Unload SDK” button. In this case you will see the WebView killed.