Introduce DeviceInfo as a new native module

Summary:
The `UIManager` already has a lot of responsibilities and is deeply
tied with React Native's view architecture. This diff separates out a
`DeviceInfo` native module to provide information about screen dimensions and
font scale, etc.

Reviewed By: fkgozali

Differential Revision: D4713834

fbshipit-source-id: f2ee93acf876a4221c29a8c731f5abeffbb97974

Libraries/Utilities/DeviceInfo.js

@@ -0,0 +1,20 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @providesModule DeviceInfo
+ * @flow
+ */
+'use strict';
+
+const DeviceInfo = require('NativeModules').DeviceInfo;
+
+const invariant = require('invariant');
+
+invariant(DeviceInfo, 'DeviceInfo native module is not installed correctly');
+
+module.exports = DeviceInfo;

Libraries/Utilities/Dimensions.js

@@ -11,9 +11,9 @@
  */
 'use strict';
 
+var DeviceInfo = require('DeviceInfo');
 var EventEmitter = require('EventEmitter');
 var Platform = require('Platform');
-var UIManager = require('UIManager');
 var RCTDeviceEventEmitter = require('RCTDeviceEventEmitter');
 
 var invariant = require('fbjs/lib/invariant');
@@ -128,7 +128,7 @@ class Dimensions {
   }
 }
 
-Dimensions.set(UIManager.Dimensions);
+Dimensions.set(DeviceInfo.Dimensions);
 RCTDeviceEventEmitter.addListener('didUpdateDimensions', function(update) {
   Dimensions.set(update);
 });

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

@@ -85,6 +85,7 @@ const ReactNative = {
   get CameraRoll() { return require('CameraRoll'); },
   get Clipboard() { return require('Clipboard'); },
   get DatePickerAndroid() { return require('DatePickerAndroid'); },
+  get DeviceInfo() { return require('DeviceInfo'); },
   get Dimensions() { return require('Dimensions'); },
   get Easing() { return require('Easing'); },
   get I18nManager() { return require('I18nManager'); },