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

ppapi/native_client/src/trusted/plugin/service_runtime.h

Index: ppapi/native_client/src/trusted/plugin/service_runtime.h
===================================================================
--- ppapi/native_client/src/trusted/plugin/service_runtime.h	(revision 143480)
+++ ppapi/native_client/src/trusted/plugin/service_runtime.h	(working copy)
@@ -216,10 +216,12 @@
   // Spawn a sel_ldr instance and establish an SrpcClient to it.  The nexe
   // to be started is passed through |nacl_file_desc|.  On success, returns
   // true.  On failure, returns false and |error_string| is set to something
-  // describing the error.
+  // describing the error. |ipc_channel_handle| returns information for
+  // connecting the Chrome IPC-based proxy.
   bool Start(nacl::DescWrapper* nacl_file_desc,
              ErrorInfo* error_info,
-             const nacl::string& url);
+             const nacl::string& url,
+             void** ipc_channel_handle);
 
   // Starts the application channel to the nexe.
   SrpcClient* SetupAppChannel();