This folder holds the native entrypoint for all WebView processes, and is responsible for delegating to //android_webview/browser/, //android_webview/renderer/, etc.. implementations depending on what process is being started.
//android_webview/lib/ is analogous to the app folder in other content embedders. As such, it is the only path allowed to depend on native code from all processes (e.g. both //android_webview/browser/ and //android_webview/renderer/).