base: Cleanup class/struct forward declarations

base/memory/shared_memory_handle.h

 // Copyright 2015 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 BASE_MEMORY_SHARED_MEMORY_HANDLE_H_
 #define BASE_MEMORY_SHARED_MEMORY_HANDLE_H_
 
 #include <stddef.h>
 
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include "base/process/process_handle.h"
 #elif defined(OS_MACOSX) && !defined(OS_IOS)
 #include <mach/mach.h>
 #include "base/base_export.h"
 #include "base/macros.h"
 #include "base/process/process_handle.h"
 #elif defined(OS_POSIX)
 #include <sys/types.h>
 #include "base/file_descriptor_posix.h"
 #endif
 
 namespace base {
 
-class Pickle;
-
 // SharedMemoryHandle is a platform specific type which represents
 // the underlying OS handle to a shared memory segment.
 #if defined(OS_POSIX) && !(defined(OS_MACOSX) && !defined(OS_IOS))
 typedef FileDescriptor SharedMemoryHandle;
 #elif defined(OS_WIN)
 class BASE_EXPORT SharedMemoryHandle {
  public:
   // The default constructor returns an invalid SharedMemoryHandle.
   SharedMemoryHandle();
   SharedMemoryHandle(HANDLE h, base::ProcessId pid);
@@ skipping 116 matching lines @@
   // ownership of |memory_object_| to the IPC stack. This is meant to mimic
   // the behavior of the |auto_close| parameter of FileDescriptor.
   // Defaults to |false|.
   bool ownership_passes_to_ipc_ = false;
 };
 #endif
 
 }  // namespace base
 
 #endif  // BASE_MEMORY_SHARED_MEMORY_HANDLE_H_