Allow creating a NaClAppThread without creating a new host OS thread

src/trusted/service_runtime/thread_suspension_test.cc

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "native_client/src/shared/platform/nacl_log.h"
 #include "native_client/src/trusted/service_runtime/nacl_app_thread.h"
 #include "native_client/src/trusted/service_runtime/sel_ldr.h"
 #include "native_client/src/trusted/service_runtime/thread_suspension.h"
@@ skipping 97 matching lines @@
   struct NaClApp app;
   ASSERT_EQ(NaClAppCtor(&app), 1);
 
   struct NaClAppThread app_thread;
   AppThreadInitMinimal(&app_thread);
 
   struct ThreadArgs thread_args;
   thread_args.natp = NULL;
   thread_args.var = 0;
   thread_args.should_exit = false;
-  ASSERT_EQ(NaClThreadCreateJoinable(&app_thread.thread, MutatorThread,
+  app_thread.host_thread_is_defined = 1;
+  ASSERT_EQ(NaClThreadCreateJoinable(&app_thread.host_thread, MutatorThread,
                                      &thread_args, NACL_KERN_STACK_SIZE), 1);
   ASSERT_EQ(NaClAddThread(&app, &app_thread), 0);
   TrySuspendingMutatorThread(&app, &thread_args.var);
   thread_args.should_exit = true;
-  NaClThreadJoin(&app_thread.thread);
+  NaClThreadJoin(&app_thread.host_thread);
 }
 
 
 // The test below checks that we do not get a deadlock when using
 // NaClUntrustedThreadsSuspendAll() on threads that cross between
 // untrusted and trusted code by invoking NaCl syscalls.
 //
 // This is a stress test.  It is not guaranteed to find a problem, but
 // it did reproduce the problem in the original buggy version of the
 // code when Sleep() calls were inserted in suitable places.
@@ skipping 31 matching lines @@
   struct NaClApp app;
   ASSERT_EQ(NaClAppCtor(&app), 1);
 
   struct NaClAppThread app_thread;
   AppThreadInitMinimal(&app_thread);
 
   struct ThreadArgs thread_args;
   thread_args.natp = &app_thread;
   thread_args.var = 0;
   thread_args.should_exit = false;
-  ASSERT_EQ(NaClThreadCreateJoinable(&app_thread.thread, SyscallInvokerThread,
+  app_thread.host_thread_is_defined = 1;
+  ASSERT_EQ(NaClThreadCreateJoinable(&app_thread.host_thread,
+                                     SyscallInvokerThread,
                                      &thread_args, NACL_KERN_STACK_SIZE), 1);
   ASSERT_EQ(NaClAddThread(&app, &app_thread), 0);
   TrySuspendingSyscallInvokerThread(&app, &thread_args.var);
   thread_args.should_exit = true;
-  NaClThreadJoin(&app_thread.thread);
+  NaClThreadJoin(&app_thread.host_thread);
 }
 
 #endif