Support removing multiple storage listeners

Author: chrisbianca

lib/modules/storage/index.js

@@ -73,16 +73,23 @@ export default class Storage extends Base {
   }
 
   _removeListener(path: string, eventName: string, origCB: (evt: Object) => Object) {
-    if (this.subscriptions[path] && this.subscriptions[path][eventName]) {
+    if (!this.subscriptions[path] || (eventName && !this.subscriptions[path][eventName])) {
+      this.log.warn('_removeListener() called, but not currently listening at that location (bad path)', path, eventName);
+      return Promise.resolve();
+    }
+
+    if (eventName && origCB) {
       const i = this.subscriptions[path][eventName].indexOf(origCB);
 
       if (i === -1) {
         this.log.warn('_removeListener() called, but the callback specified is not listening at this location (bad path)', path, eventName);
       } else {
         this.subscriptions[path][eventName].splice(i, 1);
       }
+    } else if (eventName) {
+      this.subscriptions[path][eventName] = [];
     } else {
-      this.log.warn('_removeListener() called, but there are no listeners at this location (bad path)', path, eventName);
+      this.subscriptions[path] = {}
     }
   }