Use string16 instead of std::string when sending IPC messages.

The underlying V8::String is represented in UTF18, by using string16 in
IPC messages we can avoid the overhead of encode conversion.

atom.gyp

@@ -157,6 +157,7 @@
       'common/platform_util.h',
       'common/platform_util_mac.mm',
       'common/platform_util_win.cc',
+      'common/string16_conversions.h',
       'common/v8_value_converter_impl.cc',
       'common/v8_value_converter_impl.h',
       'renderer/api/atom_api_renderer_ipc.cc',

browser/api/atom_api_browser_ipc.cc

@@ -6,6 +6,7 @@
 
 #include "base/values.h"
 #include "common/api/api_messages.h"
+#include "common/string16_conversions.h"
 #include "common/v8_value_converter_impl.h"
 #include "content/public/browser/render_view_host.h"
 #include "vendor/node/src/node.h"
@@ -25,7 +26,7 @@ v8::Handle<v8::Value> BrowserIPC::Send(const v8::Arguments &args) {
   if (!args[0]->IsString() || !args[1]->IsNumber() || !args[2]->IsNumber())
     return node::ThrowTypeError("Bad argument");
 
-  std::string channel(*v8::String::Utf8Value(args[0]));
+  string16 channel(V8ValueToUTF16(args[0]));
   int process_id = args[1]->IntegerValue();
   int routing_id = args[2]->IntegerValue();
 

browser/api/atom_api_event.cc

@@ -4,6 +4,8 @@
 
 #include "browser/api/atom_api_event.h"
 
+#include "common/string16_conversions.h"
+
 using node::node_isolate;
 
 namespace atom {
@@ -40,10 +42,10 @@ v8::Handle<v8::Object> Event::CreateV8Object() {
 }
 
 // static
-std::string Event::GetReturnValue(v8::Handle<v8::Object> event) {
+string16 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);
+  return V8ValueToUTF16(json);
 }
 
 v8::Handle<v8::Value> Event::New(const v8::Arguments &args) {

browser/api/atom_api_event.h

@@ -5,9 +5,8 @@
 #ifndef ATOM_BROWSER_ATOM_API_EVENT_H_
 #define ATOM_BROWSER_ATOM_API_EVENT_H_
 
-#include <string>
-
 #include "base/basictypes.h"
+#include "base/string16.h"
 #include "vendor/node/src/node_object_wrap.h"
 
 namespace atom {
@@ -22,7 +21,7 @@ class Event : public node::ObjectWrap {
   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);
+  static string16 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_api_menu.cc

@@ -6,6 +6,7 @@
 
 #include "browser/api/atom_api_window.h"
 #include "browser/ui/accelerator_util.h"
+#include "common/string16_conversions.h"
 
 #define UNWRAP_MEMNU_AND_CHECK \
   Menu* self = ObjectWrap::Unwrap<Menu>(args.This()); \
@@ -18,17 +19,6 @@ namespace api {
 
 namespace {
 
-// Converts a V8 value to a string16.
-string16 V8ValueToUTF16(v8::Handle<v8::Value> value) {
-  v8::String::Value s(value);
-  return string16(reinterpret_cast<const char16*>(*s), s.length());
-}
-
-// Converts string16 to V8 String.
-v8::Handle<v8::Value> UTF16ToV8Value(const string16& s) {
-  return v8::String::New(reinterpret_cast<const uint16_t*>(s.data()), s.size());
-}
-
 // Call method of delegate object.
 v8::Handle<v8::Value> CallDelegate(v8::Handle<v8::Value> default_value,
                                    v8::Handle<v8::Object> menu,

browser/api/atom_api_window.cc

@@ -6,6 +6,7 @@
 
 #include "base/values.h"
 #include "browser/native_window.h"
+#include "common/string16_conversions.h"
 #include "common/v8_value_converter_impl.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/web_contents.h"
@@ -27,15 +28,6 @@ namespace atom {
 
 namespace api {
 
-namespace {
-
-// Converts string16 to V8 String.
-v8::Handle<v8::String> UTF16ToV8String(const string16& s) {
-  return v8::String::New(reinterpret_cast<const uint16_t*>(s.data()), s.size());
-}
-
-}  // namespace
-
 Window::Window(v8::Handle<v8::Object> wrapper, base::DictionaryValue* options)
     : EventEmitter(wrapper),
       window_(NativeWindow::Create(options)) {
@@ -473,7 +465,7 @@ v8::Handle<v8::Value> Window::GetPageTitle(const v8::Arguments &args) {
 
   string16 title = self->window_->GetWebContents()->GetTitle();
 
-  return UTF16ToV8String(title);
+  return UTF16ToV8Value(title);
 }
 
 // static

browser/api/atom_browser_bindings.cc

@@ -9,6 +9,7 @@
 #include "base/logging.h"
 #include "base/values.h"
 #include "browser/api/atom_api_event.h"
+#include "common/string16_conversions.h"
 #include "common/v8_value_converter_impl.h"
 #include "content/public/browser/browser_thread.h"
 #include "vendor/node/src/node.h"
@@ -43,7 +44,7 @@ void AtomBrowserBindings::AfterLoad() {
 
 void AtomBrowserBindings::OnRendererMessage(int process_id,
                                             int routing_id,
-                                            const std::string& channel,
+                                            const string16& channel,
                                             const base::ListValue& args) {
   v8::HandleScope scope;
 
@@ -54,7 +55,7 @@ void AtomBrowserBindings::OnRendererMessage(int process_id,
   // process.emit(channel, 'message', process_id, routing_id);
   std::vector<v8::Handle<v8::Value>> arguments;
   arguments.reserve(3 + args.GetSize());
-  arguments.push_back(v8::String::New(channel.c_str(), channel.size()));
+  arguments.push_back(UTF16ToV8Value(channel));
   const base::Value* value;
   if (args.Get(0, &value))
     arguments.push_back(converter->ToV8Value(value, context));
@@ -73,9 +74,9 @@ void AtomBrowserBindings::OnRendererMessage(int process_id,
 void AtomBrowserBindings::OnRendererMessageSync(
     int process_id,
     int routing_id,
-    const std::string& channel,
+    const string16& channel,
     const base::ListValue& args,
-    std::string* result) {
+    string16* result) {
   v8::HandleScope scope;
 
   v8::Handle<v8::Context> context = v8::Context::GetCurrent();
@@ -87,7 +88,7 @@ void AtomBrowserBindings::OnRendererMessageSync(
   // process.emit(channel, 'sync-message', event, process_id, routing_id);
   std::vector<v8::Handle<v8::Value>> arguments;
   arguments.reserve(3 + args.GetSize());
-  arguments.push_back(v8::String::New(channel.c_str(), channel.size()));
+  arguments.push_back(UTF16ToV8Value(channel));
   const base::Value* value;
   if (args.Get(0, &value))
     arguments.push_back(converter->ToV8Value(value, context));

browser/api/atom_browser_bindings.h

@@ -5,8 +5,7 @@
 #ifndef ATOM_BROWSER_API_ATOM_BROWSER_BINDINGS_
 #define ATOM_BROWSER_API_ATOM_BROWSER_BINDINGS_
 
-#include <string>
+#include "base/string16.h"
-
 #include "common/api/atom_bindings.h"
 
 namespace base {
@@ -26,15 +25,15 @@ class AtomBrowserBindings : public AtomBindings {
   // Called when received a message from renderer.
   void OnRendererMessage(int process_id,
                          int routing_id,
-                         const std::string& channel,
+                         const string16& channel,
                          const base::ListValue& args);
 
   // Called when received a synchronous message from renderer.
   void OnRendererMessageSync(int process_id,
                              int routing_id,
-                             const std::string& channel,
+                             const string16& channel,
                              const base::ListValue& args,
-                             std::string* result);
+                             string16* result);
 
   // The require('atom').browserMainParts object.
   v8::Handle<v8::Object> browser_main_parts() {

browser/native_window.cc

@@ -341,7 +341,7 @@ void NativeWindow::Observe(int type,
   }
 }
 
-void NativeWindow::OnRendererMessage(const std::string& channel,
+void NativeWindow::OnRendererMessage(const string16& channel,
                                      const base::ListValue& args) {
   AtomBrowserMainParts::Get()->atom_bindings()->OnRendererMessage(
       GetWebContents()->GetRenderProcessHost()->GetID(),
@@ -350,10 +350,10 @@ void NativeWindow::OnRendererMessage(const std::string& channel,
       args);
 }
 
-void NativeWindow::OnRendererMessageSync(const std::string& channel,
+void NativeWindow::OnRendererMessageSync(const string16& channel,
                                          const base::ListValue& args,
                                          IPC::Message* reply_msg) {
-  std::string json;
+  string16 json;
   AtomBrowserMainParts::Get()->atom_bindings()->OnRendererMessageSync(
       GetWebContents()->GetRenderProcessHost()->GetID(),
       GetWebContents()->GetRoutingID(),

browser/native_window.h

@@ -177,10 +177,10 @@ class NativeWindow : public brightray::DefaultWebContentsDelegate,
  private:
   void RendererUnresponsiveDelayed();
 
-  void OnRendererMessage(const std::string& channel,
+  void OnRendererMessage(const string16& channel,
                          const base::ListValue& args);
 
-  void OnRendererMessageSync(const std::string& channel,
+  void OnRendererMessageSync(const string16& channel,
                              const base::ListValue& args,
                              IPC::Message* reply_msg);
 

common/api/api_messages.h

@@ -4,8 +4,7 @@
 
 // Multiply-included file, no traditional include guard.
 
-#include <string>
+#include "base/string16.h"
-
 #include "base/values.h"
 #include "common/draggable_region.h"
 #include "content/public/common/common_param_traits.h"
@@ -22,16 +21,16 @@ IPC_STRUCT_TRAITS_BEGIN(atom::DraggableRegion)
 IPC_STRUCT_TRAITS_END()
 
 IPC_MESSAGE_ROUTED2(AtomViewHostMsg_Message,
-                    std::string /* channel */,
+                    string16 /* channel */,
                     ListValue /* arguments */)
 
 IPC_SYNC_MESSAGE_ROUTED2_1(AtomViewHostMsg_Message_Sync,
-                           std::string /* channel */,
+                           string16 /* channel */,
                            ListValue /* arguments */,
-                           std::string /* result (in JSON) */)
+                           string16 /* result (in JSON) */)
 
 IPC_MESSAGE_ROUTED2(AtomViewMsg_Message,
-                    std::string /* channel */,
+                    string16 /* channel */,
                     ListValue /* arguments */)
 
 // Sent by the renderer when the draggable regions are updated.

common/string16_conversions.h

@@ -0,0 +1,23 @@
+// Copyright (c) 2013 GitHub, Inc. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMMON_STRING16_CONVERSIONS_H_
+#define COMMON_STRING16_CONVERSIONS_H_
+
+#include "v8/include/v8.h"
+
+class string16;
+
+// Converts a V8 value to a string16.
+inline string16 V8ValueToUTF16(v8::Handle<v8::Value> value) {
+  v8::String::Value s(value);
+  return string16(reinterpret_cast<const char16*>(*s), s.length());
+}
+
+// Converts string16 to V8 String.
+inline v8::Handle<v8::Value> UTF16ToV8Value(const string16& s) {
+  return v8::String::New(reinterpret_cast<const uint16_t*>(s.data()), s.size());
+}
+
+#endif  // COMMON_STRING16_CONVERSIONS_H_

renderer/api/atom_api_renderer_ipc.cc

@@ -6,6 +6,7 @@
 
 #include "base/values.h"
 #include "common/api/api_messages.h"
+#include "common/string16_conversions.h"
 #include "content/public/renderer/render_view.h"
 #include "content/public/renderer/v8_value_converter.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebFrame.h"
@@ -47,8 +48,7 @@ v8::Handle<v8::Value> RendererIPC::Send(const v8::Arguments &args) {
   if (!args[0]->IsString())
     return node::ThrowTypeError("Bad argument");
 
-  std::string channel(*v8::String::Utf8Value(args[0]));
+  string16 channel(V8ValueToUTF16(args[0]));
-
   RenderView* render_view = GetCurrentRenderView();
 
   // Convert Arguments to Array, so we can use V8ValueConverter to convert it
@@ -82,7 +82,7 @@ v8::Handle<v8::Value> RendererIPC::SendSync(const v8::Arguments &args) {
     return node::ThrowTypeError("Bad argument");
 
   v8::Handle<v8::Context> context = v8::Context::GetCurrent();
-  std::string channel(*v8::String::Utf8Value(args[0]));
+  string16 channel(V8ValueToUTF16(args[0]));
 
   // Convert Arguments to Array, so we can use V8ValueConverter to convert it
   // to ListValue.
@@ -97,7 +97,7 @@ v8::Handle<v8::Value> RendererIPC::SendSync(const v8::Arguments &args) {
 
   RenderView* render_view = GetCurrentRenderView();
 
-  std::string json;
+  string16 json;
   IPC::SyncMessage* message = new AtomViewHostMsg_Message_Sync(
       render_view->GetRoutingID(),
       channel,
@@ -110,7 +110,7 @@ v8::Handle<v8::Value> RendererIPC::SendSync(const v8::Arguments &args) {
   if (!success)
     return node::ThrowError("Unable to send AtomViewHostMsg_Message_Sync");
 
-  return scope.Close(v8::String::New(json.data(), json.size()));
+  return scope.Close(UTF16ToV8Value(json));
 }
 
 // static

renderer/api/atom_renderer_bindings.cc

@@ -8,6 +8,7 @@
 
 #include "base/logging.h"
 #include "base/values.h"
+#include "common/string16_conversions.h"
 #include "content/public/renderer/render_view.h"
 #include "content/public/renderer/v8_value_converter.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebFrame.h"
@@ -51,7 +52,7 @@ void AtomRendererBindings::BindToFrame(WebFrame* frame) {
   AtomBindings::BindTo(GetProcessObject(context));
 }
 
-void AtomRendererBindings::OnBrowserMessage(const std::string& channel,
+void AtomRendererBindings::OnBrowserMessage(const string16& channel,
                                             const base::ListValue& args) {
   if (!render_view_->GetWebView())
     return;
@@ -70,7 +71,7 @@ void AtomRendererBindings::OnBrowserMessage(const std::string& channel,
 
   std::vector<v8::Handle<v8::Value>> arguments;
   arguments.reserve(1 + args.GetSize());
-  arguments.push_back(v8::String::New(channel.c_str(), channel.size()));
+  arguments.push_back(UTF16ToV8Value(channel));
 
   for (size_t i = 0; i < args.GetSize(); i++) {
     const base::Value* value;

renderer/api/atom_renderer_bindings.h

@@ -5,10 +5,10 @@
 #ifndef ATOM_RENDERER_API_ATOM_RENDERER_BINDINGS_H_
 #define ATOM_RENDERER_API_ATOM_RENDERER_BINDINGS_H_
 
-#include <string>
-
 #include "common/api/atom_bindings.h"
 
+#include "base/string16.h"
+
 namespace base {
 class ListValue;
 }
@@ -32,7 +32,7 @@ class AtomRendererBindings : public AtomBindings {
   void BindToFrame(WebKit::WebFrame* frame);
 
   // Dispatch messages from browser.
-  void OnBrowserMessage(const std::string& channel,
+  void OnBrowserMessage(const string16& channel,
                         const base::ListValue& args);
 
  private:

renderer/atom_render_view_observer.cc

@@ -101,7 +101,7 @@ bool AtomRenderViewObserver::OnMessageReceived(const IPC::Message& message) {
   return handled;
 }
 
-void AtomRenderViewObserver::OnBrowserMessage(const std::string& channel,
+void AtomRenderViewObserver::OnBrowserMessage(const string16& channel,
                                               const base::ListValue& args) {
   atom_bindings()->OnBrowserMessage(channel, args);
 }

renderer/atom_render_view_observer.h

@@ -35,7 +35,7 @@ class AtomRenderViewObserver : content::RenderViewObserver {
   virtual void DraggableRegionsChanged(WebKit::WebFrame* frame) OVERRIDE;
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
-  void OnBrowserMessage(const std::string& channel,
+  void OnBrowserMessage(const string16& channel,
                         const base::ListValue& args);
 
   scoped_ptr<AtomRendererBindings> atom_bindings_;