Reuse Subscriber flow type definition in more places

Author: philikon

src/LocalSubscriptions.js

@@ -28,6 +28,8 @@ var Id = require('./Id');
 var ObjectStore = require('./ObjectStore');
 var Parse = require('./StubParse');
 
+import type { Subscriber } from './Subscription';
+
 /**
  * Local Subscriptions allow applications to subscribe to local objects, such
  * as the current user. React components can watch these for changes and
@@ -38,9 +40,7 @@ var currentUser = {
   subscribers: {},
   observerCount: 0,
 
-  subscribe: function(
-      callbacks:{ onNext: (value: any) => void; onError?: (error: any) => void }
-    ): { dispose: () => void } {
+  subscribe: function(callbacks: Subscriber): { dispose: () => void } {
     var observerId = 'o' + this.observerCount++;
     this.subscribers[observerId] = callbacks;
     var id;

src/Subscription.js

@@ -30,7 +30,7 @@ type ParseObject = {
   id: Id
 };
 
-type Subscriber = {
+export type Subscriber = {
   onNext: (value: any) => void;
   onError?: (error: any) => void;
 };

src/SubscriptionManager.js

@@ -30,6 +30,8 @@ var keysFromHash = QueryTools.keysFromHash;
 var queryHash = QueryTools.queryHash;
 var Subscription = require('./Subscription');
 
+import type { Subscriber } from './Subscription';
+
 // Mapping of query hashes to subscriptions
 var subscriptions = {};
 // Tree of the attributes queries depend on, leading to their hashes
@@ -42,7 +44,7 @@ var queryFamilies = {};
  */
 function subscribeToQuery(
     query: any,
-    callbacks: { onNext: (value: any) => void; onError?: (error: any) => void }
+    callbacks: Subscriber
   ): { refresh: () => void; dispose: () => void } {
   var hash = queryHash(query);
   var subscription = subscriptions[hash];