Resupport cross-process callback.

It seems that it's avoidable to make callback cross-process when we
start to emitting events for GUI elements, without this feature our
implementation will be much more complicated. I will find a way to warn
about resources leak in browser.

browser/atom/rpc_server.coffee

@@ -1,15 +1,22 @@
 ipc = require 'ipc'
 path = require 'path'
 objectsRegistry = require './objects_registry.js'
+v8_util = process.atomBinding 'v8_util'
 
-metaToArgs = (metas) ->
-  metas.map (meta) ->
-    if meta.type is 'value'
-      meta.value
-    else if meta.type is 'remoteObject'
-      objectsRegistry.get meta.id
+unwrapArgs = (processId, routingId, args) ->
+  args.map (arg) ->
+    if arg.type is 'value'
+      arg.value
+    else if arg.type is 'remoteObject'
+      objectsRegistry.get arg.id
+    else if arg.type is 'function'
+      ret = ->
+        ipc.sendChannel processId, routingId, 'ATOM_RENDERER_CALLBACK', arg.id, new Meta(processId, routingId, arguments)
+      v8_util.setDestructor ret, ->
+        ipc.sendChannel processId, routingId, 'ATOM_RENDERER_RELEASE_CALLBACK', arg.id
+      ret
     else
-      throw new TypeError("Unknown type: #{meta.type}")
+      throw new TypeError("Unknown type: #{arg.type}")
 
 # Convert a real value into a POD structure which carries information of this
 # value.
@@ -67,7 +74,7 @@ ipc.on 'ATOM_BROWSER_CURRENT_WINDOW', (event, processId, routingId) ->
 
 ipc.on 'ATOM_BROWSER_CONSTRUCTOR', (event, processId, routingId, id, args) ->
   try
-    args = metaToArgs args
+    args = unwrapArgs processId, routingId, args
     constructor = objectsRegistry.get id
     # Call new with array of arguments.
     # http://stackoverflow.com/questions/1606797/use-of-apply-with-new-operator-is-this-possible
@@ -78,7 +85,7 @@ ipc.on 'ATOM_BROWSER_CONSTRUCTOR', (event, processId, routingId, id, args) ->
 
 ipc.on 'ATOM_BROWSER_FUNCTION_CALL', (event, processId, routingId, id, args) ->
   try
-    args = metaToArgs args
+    args = unwrapArgs processId, routingId, args
     func = objectsRegistry.get id
     ret = func.apply global, args
     event.result = new Meta(processId, routingId, ret)
@@ -87,7 +94,7 @@ ipc.on 'ATOM_BROWSER_FUNCTION_CALL', (event, processId, routingId, id, args) ->
 
 ipc.on 'ATOM_BROWSER_MEMBER_CALL', (event, processId, routingId, id, method, args) ->
   try
-    args = metaToArgs args
+    args = unwrapArgs processId, routingId, args
     obj = objectsRegistry.get id
     ret = obj[method].apply(obj, args)
     event.result = new Meta(processId, routingId, ret)

renderer/api/lib/remote.coffee

@@ -1,16 +1,30 @@
 ipc = require 'ipc'
 v8_util = process.atomBinding 'v8_util'
 
+nextCallbackId = 0
+storedCallbacks = {}
+
+storeCallback = (callback) ->
+  ++nextCallbackId
+  storedCallbacks[nextCallbackId] = callback
+  nextCallbackId
+
+makeCallback = (id, args) ->
+  storedCallbacks[id].apply global, args
+
+releaseCallback = (id) ->
+  delete storedCallbacks[id]
+
 # Transform the arguments passed to browser into list of descriptions.
 #
 # This function assumes an array is passed, and it only converts remote objects
 # and functions, other types of values are passed as it is.
-argsToMeta = (args) ->
-  args.map (value) ->
+wrapArgs = (args) ->
+  Array::slice.call(args).map (value) ->
     if typeof value is 'object' and v8_util.getHiddenValue value, 'isRemoteObject'
       type: 'remoteObject', id: value.id
     else if typeof value is 'function'
-      throw new TypeError('functions is not supported yet')
+      type: 'function', id: storeCallback(value)
     else
       type: 'value', value: value
 
@@ -28,7 +42,7 @@ metaToValue = (meta) ->
           constructor: ->
             if @constructor == RemoteFunction
               # Constructor call.
-              obj = ipc.sendChannelSync 'ATOM_BROWSER_CONSTRUCTOR', meta.id, Array::slice.call(arguments)
+              obj = ipc.sendChannelSync 'ATOM_BROWSER_CONSTRUCTOR', meta.id, wrapArgs(arguments)
 
               # Returning object in constructor will replace constructed object
               # with the returned object.
@@ -36,7 +50,7 @@ metaToValue = (meta) ->
               return metaToValue obj
             else
               # Function call.
-              ret = ipc.sendChannelSync 'ATOM_BROWSER_FUNCTION_CALL', meta.id, Array::slice.call(arguments)
+              ret = ipc.sendChannelSync 'ATOM_BROWSER_FUNCTION_CALL', meta.id, wrapArgs(arguments)
               return metaToValue ret
       else
         ret = v8_util.createObjectWithName meta.name
@@ -47,7 +61,7 @@ metaToValue = (meta) ->
           if member.type is 'function'
             ret[member.name] = ->
               # Call member function.
-              ret = ipc.sendChannelSync 'ATOM_BROWSER_MEMBER_CALL', meta.id, member.name, Array::slice.call(arguments)
+              ret = ipc.sendChannelSync 'ATOM_BROWSER_MEMBER_CALL', meta.id, member.name, wrapArgs(arguments)
               metaToValue ret
           else
             ret.__defineSetter__ member.name, (value) ->
@@ -69,6 +83,12 @@ metaToValue = (meta) ->
 
       ret
 
+ipc.on 'ATOM_RENDERER_CALLBACK', (id, args) ->
+  makeCallback id, metaToValue(args)
+
+ipc.on 'ATOM_RENDERER_RELEASE_CALLBACK', (id) ->
+  releaseCallback id
+
 # Release all resources of current render view when it's going to be unloaded.
 window.addEventListener 'unload', (event) ->
   ipc.sendChannelSync 'ATOM_BROWSER_RELEASE_RENDER_VIEW'