Pass synchronous messages by JSON string.

We are going to use IPC_MESSAGE_HANDLER_DELAY_REPLY to handle
synchronous messages but DictionaryValue is not copyable, so we pass the
JSON string instead.

browser/api/atom_api_event.cc

@@ -39,6 +39,13 @@ v8::Handle<v8::Object> Event::CreateV8Object() {
   return scope.Close(v8_event);
 }
 
+// static
+std::string Event::GetReturnValue(v8::Handle<v8::Object> event) {
+  v8::HandleScope scope;
+  v8::Local<v8::Value> json = event->Get(v8::String::New("returnValue"));
+  return *v8::String::Utf8Value(json);
+}
+
 v8::Handle<v8::Value> Event::New(const v8::Arguments &args) {
   Event* event = new Event;
   event->Wrap(args.This());

browser/api/atom_api_event.h

@@ -5,6 +5,8 @@
 #ifndef ATOM_BROWSER_ATOM_API_EVENT_H_
 #define ATOM_BROWSER_ATOM_API_EVENT_H_
 
+#include <string>
+
 #include "base/basictypes.h"
 #include "vendor/node/src/node_object_wrap.h"
 
@@ -19,6 +21,9 @@ class Event : public node::ObjectWrap {
   // Create a V8 Event object.
   static v8::Handle<v8::Object> CreateV8Object();
 
+  // Get JSON string of the event.returnValue from a Event object.
+  static std::string GetReturnValue(v8::Handle<v8::Object> event);
+
   // Accessor to return handle_, this follows Google C++ Style.
   v8::Persistent<v8::Object>& handle() { return handle_; }
 

browser/api/atom_browser_bindings.cc

@@ -8,6 +8,7 @@
 
 #include "base/logging.h"
 #include "base/values.h"
+#include "browser/api/atom_api_event.h"
 #include "common/v8_value_converter_impl.h"
 #include "content/public/browser/browser_thread.h"
 #include "vendor/node/src/node.h"
@@ -74,7 +75,7 @@ void AtomBrowserBindings::OnRendererMessageSync(
     int routing_id,
     const std::string& channel,
     const base::ListValue& args,
-    base::DictionaryValue* result) {
+    std::string* result) {
   v8::HandleScope scope;
 
   v8::Handle<v8::Context> context = v8::Context::GetCurrent();
@@ -101,11 +102,7 @@ void AtomBrowserBindings::OnRendererMessageSync(
   }
 
   node::MakeCallback(node::process, "emit", arguments.size(), &arguments[0]);
-
-  scoped_ptr<base::Value> base_event(converter->FromV8Value(event, context));
-  DCHECK(base_event && base_event->IsType(base::Value::TYPE_DICTIONARY));
-
-  result->Swap(static_cast<base::DictionaryValue*>(base_event.get()));
+  *result = api::Event::GetReturnValue(event);
 }
 
 }  // namespace atom

browser/api/atom_browser_bindings.h

@@ -10,7 +10,6 @@
 #include "common/api/atom_bindings.h"
 
 namespace base {
-class DictionaryValue;
 class ListValue;
 }
 
@@ -35,7 +34,7 @@ class AtomBrowserBindings : public AtomBindings {
                              int routing_id,
                              const std::string& channel,
                              const base::ListValue& args,
-                             base::DictionaryValue* result);
+                             std::string* result);
 
   // The require('atom').browserMainParts object.
   v8::Handle<v8::Object> browser_main_parts() {

browser/api/lib/ipc.coffee

@@ -14,8 +14,15 @@ class Ipc extends EventEmitter
   constructor: ->
     process.on 'ATOM_INTERNAL_MESSAGE', (args...) =>
       @emit(args...)
-    process.on 'ATOM_INTERNAL_MESSAGE_SYNC', (args...) =>
-      @emit(args...)
+    process.on 'ATOM_INTERNAL_MESSAGE_SYNC', (channel, event, args...) =>
+      returnValue = 'null'
+      get = -> returnValue
+      set = (value) -> returnValue = JSON.stringify(value)
+
+      Object.defineProperty event, 'returnValue', {get, set}
+      Object.defineProperty event, 'result', {get, set}
+
+      @emit(channel, event, args...)
 
   send: (processId, routingId, args...) ->
     @sendChannel(processId, routingId, 'message', args...)