RFC: Add an interface for having the browser open a pnacl support file

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 5dff4e01441c56a0089106cb4fec6b367973db92..8c72f26c85341f3a314631629807b4e671fdd43d 100644
--- a/chrome/browser/renderer_host/chrome_render_message_filter.cc
+++ b/chrome/browser/renderer_host/chrome_render_message_filter.cc
@@ -19,6 +19,7 @@
 #include "chrome/browser/extensions/extension_process_manager.h"
 #include "chrome/browser/metrics/histogram_synchronizer.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"
@@ -68,6 +69,8 @@ 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_RendererHistograms,
@@ -161,6 +164,13 @@ void ChromeRenderMessageFilter::OnLaunchNaCl(
     Send(reply_msg);
   }
 }
+
+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(