[mojo] Implement pipe fusion API

mojo/public/platform/native/system_thunks.cc

Index: mojo/public/platform/native/system_thunks.cc
diff --git a/mojo/public/platform/native/system_thunks.cc b/mojo/public/platform/native/system_thunks.cc
index fd14d486da6078c01398997f615427563a05c8d2..72d879b5eaf93532a747514fa8c2213c9429bf2e 100644
--- a/mojo/public/platform/native/system_thunks.cc
+++ b/mojo/public/platform/native/system_thunks.cc
@@ -200,6 +200,11 @@ MojoResult MojoCancelWatch(MojoHandle handle, uintptr_t context) {
   return g_thunks.CancelWatch(handle, context);
 }
 
+MojoResult MojoFuseMessagePipes(MojoHandle handle0, MojoHandle handle1) {
+  assert(g_thunks.FuseMessagePipes);
+  return g_thunks.FuseMessagePipes(handle0, handle1);
+}
+
 extern "C" THUNK_EXPORT size_t MojoSetSystemThunks(
     const MojoSystemThunks* system_thunks) {
   if (system_thunks->size >= sizeof(g_thunks))