[WebView] Add props for overriding native component

Libraries/Components/WebView/WebView.android.js

@@ -160,6 +160,18 @@ class WebView extends React.Component {
      * @platform android
      */
     allowUniversalAccessFromFileURLs: PropTypes.bool,
+
+    /**
+     * Override the native component used to render the WebView. Enables a custom native 
+     * WebView which uses the same JavaScript as the original WebView.
+     */
+    nativeComponent: PropTypes.any,
+
+    /**
+     * Set props directly on the native component WebView. Enables custom props which the
+     * original WebView doesn't pass through.
+     */
+    nativeComponentProps: PropTypes.object
   };
 
   static defaultProps = {
@@ -214,8 +226,11 @@ class WebView extends React.Component {
       console.warn('WebView: `source.body` is not supported when using GET.');
     }
 
+    let NativeWebView = this.props.nativeComponent || RCTWebView;
+
     var webView =
-      <RCTWebView
+      <NativeWebView
+        {...this.props.nativeComponentProps}
         ref={RCT_WEBVIEW_REF}
         key="webViewKey"
         style={webViewStyles}

Libraries/Components/WebView/WebView.ios.js

@@ -334,6 +334,18 @@ class WebView extends React.Component {
      * to tap them before they start playing. The default value is `true`.
      */
     mediaPlaybackRequiresUserAction: PropTypes.bool,
+
+    /**
+     * Override the native component used to render the WebView. Enables a custom native 
+     * WebView which uses the same JavaScript as the original WebView.
+     */
+    nativeComponent: PropTypes.any,
+
+    /**
+     * Set props directly on the native component WebView. Enables custom props which the
+     * original WebView doesn't pass through.
+     */
+    nativeComponentProps: PropTypes.object
   };
 
   state = {
@@ -394,8 +406,11 @@ class WebView extends React.Component {
 
     const messagingEnabled = typeof this.props.onMessage === 'function';
 
+    let NativeWebView = this.props.nativeComponent || RCTWebView;
+
     var webView =
-      <RCTWebView
+      <NativeWebView
+        {...this.props.nativeComponentProps}
         ref={RCT_WEBVIEW_REF}
         key="webViewKey"
         style={webViewStyles}