Thread pool changes

runtime/bin/thread_pool.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/thread_pool.h"
 
 void ThreadPool::Shutdown() {
   UNIMPLEMENTED();
 }
 
 
 void ThreadPool::InsertTask(Task task) {
   TaskQueueEntry* entry = new TaskQueueEntry(task);
   queue.Insert(entry);
 }
 
 
 Task ThreadPool::WaitForTask() {
   TaskQueueEntry* entry = queue.Remove();
   if (entry == NULL) {
-    return -1;
+    return NULL;
   }
   Task task = entry->task();
   delete entry;
   return task;
 }
 
 
 void* ThreadPool::Main(void* args) {
   if (Dart_IsVMFlagSet("trace_thread_pool")) {
     printf("Thread pool thread started\n");
   }
   ThreadPool* pool = reinterpret_cast<ThreadPool*>(args);
   while (true) {
     if (Dart_IsVMFlagSet("trace_thread_pool")) {
       printf("Waiting for task\n");
     }
     Task task = pool->WaitForTask();
-    if (Dart_IsVMFlagSet("trace_thread_pool")) {
-      printf("Got task %d\n", task);
-    }
+    (*(pool->task_handler_))(task);
   }
   return NULL;
 };