Add an IPC channel between the NaCl loader process and the renderer.

chrome/browser/nacl_host/nacl_process_host.cc

Index: chrome/browser/nacl_host/nacl_process_host.cc
===================================================================
--- chrome/browser/nacl_host/nacl_process_host.cc	(revision 143509)
+++ chrome/browser/nacl_host/nacl_process_host.cc	(working copy)
@@ -145,6 +145,9 @@
       getenv("NACL_UNTRUSTED_EXCEPTION_HANDLING") != NULL) {
     enable_exception_handling_ = true;
   }
+
+  enable_ipc_proxy_ = CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnableNaClIPCProxy);
 }
 
 NaClProcessHost::~NaClProcessHost() {
@@ -537,6 +540,8 @@
     IPC_MESSAGE_HANDLER_DELAY_REPLY(NaClProcessMsg_AttachDebugExceptionHandler,
                                     OnAttachDebugExceptionHandler)
 #endif
+    IPC_MESSAGE_HANDLER(NaClProcessHostMsg_PpapiChannelCreated,
+                        OnPpapiChannelCreated)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
@@ -556,7 +561,8 @@
   }
 }
 
-bool NaClProcessHost::ReplyToRenderer() {
+bool NaClProcessHost::ReplyToRenderer(
+    const IPC::ChannelHandle& channel_handle) {
   std::vector<nacl::FileDescriptor> handles_for_renderer;
   for (size_t i = 0; i < internal_->sockets_for_renderer.size(); i++) {
 #if defined(OS_WIN)
@@ -600,7 +606,7 @@
 #endif
 
   ChromeViewHostMsg_LaunchNaCl::WriteReplyParams(
-      reply_msg_, handles_for_renderer);
+      reply_msg_, handles_for_renderer, channel_handle);
   chrome_render_message_filter_->Send(reply_msg_);
   chrome_render_message_filter_ = NULL;
   reply_msg_ = NULL;
@@ -618,6 +624,7 @@
   params.enable_exception_handling = enable_exception_handling_;
   params.enable_debug_stub =
       CommandLine::ForCurrentProcess()->HasSwitch(switches::kEnableNaClDebug);
+  params.enable_ipc_proxy = enable_ipc_proxy_;
 
   base::PlatformFile irt_file = nacl_browser->IrtFile();
   CHECK_NE(irt_file, base::kInvalidPlatformFileValue);
@@ -665,9 +672,19 @@
 }
 
 bool NaClProcessHost::SendStart() {
-  return ReplyToRenderer() && StartNaClExecution();
+  if (!enable_ipc_proxy_) {
+    if (!ReplyToRenderer(IPC::ChannelHandle()))
+      return false;
+  }
+  return StartNaClExecution();
 }
 
+void NaClProcessHost::OnPpapiChannelCreated(
+    const IPC::ChannelHandle& channel_handle) {
+  DCHECK(enable_ipc_proxy_);
+  ReplyToRenderer(channel_handle);
+}
+
 bool NaClProcessHost::StartWithLaunchedProcess() {
 #if defined(OS_LINUX)
   if (wait_for_nacl_gdb_) {