Android 4.4 (KitKat) includes a new WebView component based on the Chromium open source project. The new WebView includes an updated version of the V8 JavaScript engine and support for modern web standards that were missing in the old WebView. It also shares the same rendering engine as Chrome for Android, so rendering should be much more consistent between the WebView and Chrome.
If you're a web developer looking to start developing a WebView-based Android application, see Getting Started: WebView-based Applications for Web Developers.
Source: https://developers.google.com/chrome/mobile/docs/webview/overview
