Add a NaCl-Private interface for opening files in DIR_PNACL_COMPONENT.

chrome/browser/renderer_host/chrome_render_message_filter.cc

Index: chrome/browser/renderer_host/chrome_render_message_filter.cc
diff --git a/chrome/browser/renderer_host/chrome_render_message_filter.cc b/chrome/browser/renderer_host/chrome_render_message_filter.cc
index 321825c6b490d731d023f40b6197aa3c9266454d..a4d55a064559eb4cdfbed54b11559db042181d87 100644
--- a/chrome/browser/renderer_host/chrome_render_message_filter.cc
+++ b/chrome/browser/renderer_host/chrome_render_message_filter.cc
@@ -20,6 +20,7 @@
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_system.h"
 #include "chrome/browser/nacl_host/nacl_process_host.h"
+#include "chrome/browser/nacl_host/pnacl_file_host.h"
 #include "chrome/browser/net/chrome_url_request_context.h"
 #include "chrome/browser/net/predictor.h"
 #include "chrome/browser/profiles/profile.h"
@@ -73,6 +74,8 @@ bool ChromeRenderMessageFilter::OnMessageReceived(const IPC::Message& message,
   IPC_BEGIN_MESSAGE_MAP_EX(ChromeRenderMessageFilter, message, *message_was_ok)
 #if !defined(DISABLE_NACL)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(ChromeViewHostMsg_LaunchNaCl, OnLaunchNaCl)
+    IPC_MESSAGE_HANDLER_DELAY_REPLY(ChromeViewHostMsg_GetReadonlyPnaclFD,
+                                    OnGetReadonlyPnaclFd)
 #endif
     IPC_MESSAGE_HANDLER(ChromeViewHostMsg_DnsPrefetch, OnDnsPrefetch)
     IPC_MESSAGE_HANDLER(ChromeViewHostMsg_ResourceTypeStats,
@@ -169,6 +172,13 @@ void ChromeRenderMessageFilter::OnLaunchNaCl(const GURL& manifest_url,
   NaClProcessHost* host = new NaClProcessHost(manifest_url, off_the_record_);
   host->Launch(this, socket_count, reply_msg, extension_info_map_);
 }
+
+void ChromeRenderMessageFilter::OnGetReadonlyPnaclFd(
+    const std::string& filename, IPC::Message* reply_msg) {
+  // This posts a task to another thread, but the renderer will
+  // block until the reply is sent.
+  pnacl_file_host::GetReadonlyPnaclFd(this, filename, reply_msg);
+}
 #endif
 
 void ChromeRenderMessageFilter::OnDnsPrefetch(