[both] continued work on multi app support - storage now full supported and auth WIP

lib/utils/ModuleBase.js

@@ -1,10 +1,11 @@
 /**
  * @flow
  */
-import { NativeModules, NativeEventEmitter } from 'react-native';
+import { NativeModules } from 'react-native';
 import Log from '../utils/log';
 import { nativeWithApp } from './../utils';
 import INTERNALS from './../internals';
+import FirebaseCore from './../firebase';
 
 const logs = {};
 
@@ -15,6 +16,16 @@ const MULTI_APP_MODULES = [
   'storage',
 ];
 
+const NATIVE_MODULE_EVENTS = {
+  Storage: [
+    'storage_event',
+    'storage_error',
+  ],
+  Auth: [
+    'onAuthStateChanged',
+  ],
+};
+
 export default class ModuleBase {
   constructor(firebaseApp, options, moduleName, withEventEmitter = false) {
     this._options = Object.assign({}, options);
@@ -23,14 +34,16 @@ export default class ModuleBase {
     this._appName = firebaseApp.name;
     this._namespace = `${this._appName}:${this._module}`;
 
-    // check if native module exists as all native modules are now optionally part of build
+    // check if native module exists as all native
+    // modules are now optionally part of build
     const nativeModule = NativeModules[`RNFirebase${moduleName}`];
 
     if (!nativeModule) {
       throw new Error(INTERNALS.STRINGS.ERROR_MISSING_MODULE(moduleName));
     }
 
-    // used by the modules that extend ModuleBase to access their native module counterpart
+    // used by the modules that extend ModuleBase
+    // to access their native module counterpart
     if (!MULTI_APP_MODULES.includes(moduleName.toLowerCase())) {
       this._native = nativeModule;
     } else {
@@ -38,10 +51,37 @@ export default class ModuleBase {
     }
 
     if (withEventEmitter) {
-      this._eventEmitter = new NativeEventEmitter(this._native);
+      this._setupEventEmitter(nativeModule, moduleName);
     }
   }
 
+  /**
+   *
+   * @param nativeModule
+   * @param moduleName
+   * @private
+   */
+  _setupEventEmitter(nativeModule, moduleName) {
+    this._eventEmitter = FirebaseCore._getOrSetNativeEmitter(this._appName, nativeModule);
+    const events = NATIVE_MODULE_EVENTS[moduleName];
+
+    if (events && events.length) {
+      for (let i = 0, len = events.length; i < len; i++) {
+        FirebaseCore._subscribeForDistribution(events[i], this._eventEmitter);
+      }
+    }
+  }
+
+  /**
+   *
+   * @param eventName
+   * @return {string}
+   * @private
+   */
+  _getAppEventName(eventName) {
+    return `${this._appName}-${eventName}`;
+  }
+
   /**
    * Returns the FirebaseApp instance for current module
    * @return {*}