content: Cleanup class/struct forward declarations

content/zygote/zygote_linux.h

 // 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.
 
 #ifndef CONTENT_ZYGOTE_ZYGOTE_LINUX_H_
 #define CONTENT_ZYGOTE_ZYGOTE_LINUX_H_
 
 #include <stddef.h>
 
 #include <string>
 #include <vector>
 
 #include "base/containers/small_map.h"
 #include "base/files/scoped_file.h"
 #include "base/memory/scoped_vector.h"
 #include "base/posix/global_descriptors.h"
 #include "base/process/kill.h"
 #include "base/process/process.h"
 #include "base/process/process_handle.h"
 #include "base/time/time.h"
 
 namespace base {
-class Pickle;
 class PickleIterator;
 }
 
 namespace content {
 
 class ZygoteForkDelegate;
 
 // This is the object which implements the zygote. The ZygoteMain function,
 // which is called from ChromeMain, simply constructs one of these objects and
 // runs it.
@@ skipping 118 matching lines @@
   // children.
   std::vector<int> extra_fds_;
 
   // The vector contains the child processes that need to be reaped.
   std::vector<ZygoteProcessInfo> to_reap_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_ZYGOTE_ZYGOTE_LINUX_H_