fix(background-mode): add missing method (#1486)

fix #1393

src/@ionic-native/plugins/background-mode/index.ts

@@ -150,6 +150,15 @@ export class BackgroundMode extends IonicNativePlugin {
   })
   moveToBackground(): void { }
 
+  /**
+   * Enable GPS-tracking in background (Android).
+   */
+  @Cordova({
+    platforms: ['Android'],
+    sync: true
+  })
+  disableWebViewOptimizations (): void { }
+
   /**
    * Android allows to programmatically move from background to foreground.
    */