[Android] Fix compilation error: unused variable 'kAllowedToAccessOnNonjoinableThread'

content/child/child_thread.cc

 // Copyright (c) 2012 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.
 
 #include "content/child/child_thread.h"
 
 #include <signal.h>
 
 #include <string>
 
@@ skipping 148 matching lines @@
 
 // A lock protects g_child_thread.
 base::LazyInstance<base::Lock> g_lazy_child_thread_lock =
     LAZY_INSTANCE_INITIALIZER;
 
 // base::ConditionVariable has an explicit constructor that takes
 // a base::Lock pointer as parameter. The base::DefaultLazyInstanceTraits
 // doesn't handle the case. Thus, we need our own class here.
 struct CondVarLazyInstanceTraits {
   static const bool kRegisterOnExit = true;
-  static const bool kAllowedToAccessOnNonjoinableThread ALLOW_UNUSED = false;
+#ifndef NDEBUG
+  static const bool kAllowedToAccessOnNonjoinableThread = false;
+#endif
+
   static base::ConditionVariable* New(void* instance) {
     return new (instance) base::ConditionVariable(
         g_lazy_child_thread_lock.Pointer());
   }
   static void Delete(base::ConditionVariable* instance) {
     instance->~ConditionVariable();
   }
 };
 
 // A condition variable that synchronize threads initializing and waiting
@@ skipping 349 matching lines @@
   // inflight that would addref it.
   Send(new ChildProcessHostMsg_ShutdownRequest);
 }
 
 void ChildThread::EnsureConnected() {
   VLOG(0) << "ChildThread::EnsureConnected()";
   base::KillProcess(base::GetCurrentProcessHandle(), 0, false);
 }
 
 }  // namespace content