Warn that 'WebView' has moved to 'react-native-webview'

Libraries/Utilities/warnMoved.js

@@ -0,0 +1,43 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ * @flow
+ */
+
+'use strict';
+
+const warning = require('fbjs/lib/warning');
+
+const warnedApis: {[string]: boolean} = {};
+
+/**
+ * A simple function that warns the user once if an API has been moved to
+ * another module.
+ *
+ * @param {string} api - The name of the API or component that moved
+ * @param {string} destModule - The name of the module that the API moved to
+ * @param {string} [renamed] - Optional; name of the API in the dest module,
+ *                             if it was renamed
+ */
+function warnMoved(api: string, destModule: string, renamed?: string) {
+  if (warnedApis[api]) {
+    return;
+  }
+
+  const destName = renamed != null ? renamed : api;
+
+  warning(
+    false,
+    `'${api}' has moved to another module and will be removed from 'react-native' ` +
+      `in a future release. You can instead import it from the module '${destModule}':` +
+      `\n  import {${destName}} from '${destModule}';`,
+  );
+
+  warnedApis[api] = true;
+}
+
+module.exports = warnMoved;

Libraries/react-native/react-native-implementation.js

@@ -11,6 +11,7 @@
 'use strict';
 
 const invariant = require('fbjs/lib/invariant');
+const warnMoved = require('warnMoved');
 
 let showedListViewDeprecation = false;
 let showedSwipeableListViewDeprecation = false;
@@ -170,6 +171,7 @@ module.exports = {
     return require('VirtualizedList');
   },
   get WebView() {
+    warnMoved('WebView', 'react-native-webview');
     return require('WebView');
   },