Use Mojo pipes to signal sync IPC events

ppapi/native_client/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/features.gni")
 import("//build/config/nacl/config.gni")
 
 if (is_nacl) {
   group("ppapi_lib") {
     deps = [
       "//ppapi/native_client/src/untrusted/irt_stub:ppapi_stub_lib",
     ]
   }
 
   executable("nacl_irt") {
     deps = [
       "//base",
       "//components/tracing",
       "//gpu/command_buffer/client",
       "//gpu/command_buffer/client:gles2_implementation",
       "//gpu/command_buffer/common",
       "//gpu/ipc/common:command_buffer_traits",
       "//ipc",
       "//media:shared_memory_support",
+      "//mojo/edk/system",
       "//native_client/src/shared/gio",
       "//native_client/src/shared/platform",
       "//native_client/src/tools/tls_edit($host_toolchain)",
       "//native_client/src/untrusted/irt:irt_core_lib",
       "//native_client/src/untrusted/nacl:imc_syscalls",
       "//ppapi/native_client/src/untrusted/pnacl_irt_shim:irt",
       "//ppapi/proxy",
       "//ppapi/proxy:ipc",
       "//ppapi/shared_impl",
     ]
@@ skipping 81 matching lines @@
   # On 32-bit Windows, we also ship the 64-bit IRT.
   if (is_win && target_cpu == "x86") {
     irt_x64_deps = [
       ":nacl_irt_debug(//build/toolchain/nacl:irt_x64)",
       ":nacl_irt_debuglink(//build/toolchain/nacl:irt_x64)",
     ]
     public_deps += irt_x64_deps
     data_deps += irt_x64_deps
   }
 }