Default path to Android SDK is wrong on Windows

Summary:
Default path for Android SDK was set to "/opt/android_sdk" disregard the current OS.
On Windows it should be set to "%localappdata%\android\sdk" instead.

Reviewed By: passy

Differential Revision: D19496646

fbshipit-source-id: 86ce7df74b98eef5b7b0a556a5359bec8cb0dbc4

src/reducers/settings.tsx

@@ -8,6 +8,8 @@
  */
 
 import {Actions} from './index';
+import os from 'os';
+import electron from 'electron';
 
 export enum Tristate {
   True,
@@ -40,8 +42,14 @@ export type Action =
       payload: Settings;
     };
 
+function getWindowsSdkPath() {
+  const app = electron.app || electron.remote.app;
+  return `${app.getPath('userData')}\\android\\sdk`;
+}
+
 const initialState: Settings = {
-  androidHome: '/opt/android_sdk',
+  androidHome:
+    os.platform() == 'win32' ? getWindowsSdkPath() : '/opt/android_sdk',
   enableAndroid: true,
   enablePrefetching: Tristate.Unset,
   jsApps: {