Remove unneeded uses of logging.h in header files.

base/worker_pool_linux.cc

 // Copyright (c) 2006-2008 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 "base/worker_pool.h"
 
+#include "base/logging.h"
 #include "base/task.h"
 
 namespace {
 
 void* PThreadCallback(void* param) {
   Task* task = static_cast<Task*>(param);
   task->Run();
   delete task;
   return 0;
 }
@@ skipping 16 matching lines @@
   int err = pthread_create(&thread, &attr, PThreadCallback, task);
   pthread_attr_destroy(&attr);
   if (err) {
     DLOG(ERROR) << "pthread_create failed: " << err;
     delete task;
     return false;
   }
 
   return true;
 }