Make the CallbacksRegistry a separate module, though rather small.

atom.gyp

@@ -14,6 +14,7 @@
       'browser/atom/atom.coffee',
       'browser/atom/objects_registry.coffee',
       'browser/atom/rpc_server.coffee',
+      'common/api/lib/callbacks_registry.coffee',
       'common/api/lib/clipboard.coffee',
       'common/api/lib/id_weak_map.coffee',
       'common/api/lib/shell.coffee',

browser/api/lib/dialog.coffee

@@ -1,36 +1,22 @@
 binding = process.atomBinding 'dialog'
+CallbacksRegistry = require 'callbacks_registry'
 EventEmitter = require('events').EventEmitter
 ipc = require 'ipc'
 
 FileDialog = binding.FileDialog
 FileDialog.prototype.__proto__ = EventEmitter.prototype
 
-class CallbacksRegistry
-  @nextId = 0
-  @callbacks = {}
-
-  @add: (callback) ->
-    @callbacks[++@nextId] = callback
-    @nextId
-
-  @get: (id) ->
-    @callbacks[id]
-
-  @call: (id, args...) ->
-    @callbacks[id].call global, args...
-
-  @remove: (id) ->
-    delete @callbacks[id]
+callbacksRegistry = new CallbacksRegistry
 
 fileDialog = new FileDialog
 
 fileDialog.on 'selected', (event, callbackId, paths...) ->
-  CallbacksRegistry.call callbackId, 'selected', paths...
-  CallbacksRegistry.remove callbackId
+  callbacksRegistry.call callbackId, 'selected', paths...
+  callbacksRegistry.remove callbackId
 
 fileDialog.on 'cancelled', (event, callbackId) ->
-  CallbacksRegistry.call callbackId, 'cancelled'
-  CallbacksRegistry.remove callbackId
+  callbacksRegistry.call callbackId, 'cancelled'
+  callbacksRegistry.remove callbackId
 
 validateOptions = (options) ->
   return false unless typeof options is 'object'
@@ -55,7 +41,7 @@ selectFileWrap = (window, options, callback, type, title) ->
 
   throw new TypeError('Bad arguments') unless validateOptions options
 
-  callbackId = CallbacksRegistry.add callback
+  callbackId = callbacksRegistry.add callback
 
   fileDialog.selectFile window.getProcessId(), window.getRoutingId(),
                         options.type,

common/api/lib/callbacks_registry.coffee

@@ -0,0 +1,21 @@
+module.exports =
+class CallbacksRegistry
+  constructor: ->
+    @nextId = 0
+    @callbacks = {}
+
+  add: (callback) ->
+    @callbacks[++@nextId] = callback
+    @nextId
+
+  get: (id) ->
+    @callbacks[id]
+
+  call: (id, args...) ->
+    @get(id).call global, args...
+
+  apply: (id, args...) ->
+    @get(id).apply global, args...
+
+  remove: (id) ->
+    delete @callbacks[id]

renderer/api/lib/remote.coffee

@@ -1,21 +1,9 @@
 ipc = require 'ipc'
+CallbacksRegistry = require 'callbacks_registry'
 v8_util = process.atomBinding 'v8_util'
 
 currentContextExist = true
-
-class CallbacksRegistry
-  @nextId = 0
-  @callbacks = {}
-
-  @add: (callback) ->
-    @callbacks[++@nextId] = callback
-    @nextId
-
-  @call: (id, args) ->
-    @callbacks[id].apply global, args
-
-  @remove: (id) ->
-    delete @callbacks[id]
+callbacksRegistry = new CallbacksRegistry
 
 # Convert the arguments object into an array of meta data.
 wrapArgs = (args) ->
@@ -23,7 +11,7 @@ wrapArgs = (args) ->
     if typeof value is 'object' and v8_util.getHiddenValue value, 'isRemoteObject'
       type: 'object', id: value.id
     else if typeof value is 'function'
-      type: 'function', id: CallbacksRegistry.add(value)
+      type: 'function', id: callbacksRegistry.add(value)
     else
       type: 'value', value: value
 
@@ -85,11 +73,11 @@ metaToValue = (meta) ->
 
 # Browser calls a callback in renderer.
 ipc.on 'ATOM_RENDERER_CALLBACK', (id, args) ->
-  CallbacksRegistry.call id, metaToValue(args)
+  callbacksRegistry.apply id, metaToValue(args)
 
 # A callback in browser is released.
 ipc.on 'ATOM_RENDERER_RELEASE_CALLBACK', (id) ->
-  CallbacksRegistry.remove id
+  callbacksRegistry.remove id
 
 # Release all resources of current render view when it's going to be unloaded.
 window.addEventListener 'unload', (event) ->