net: Cleanup class/struct forward declarations

net/disk_cache/blockfile/stats.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 NET_DISK_CACHE_BLOCKFILE_STATS_H_
 #define NET_DISK_CACHE_BLOCKFILE_STATS_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/strings/string_split.h"
 #include "net/base/net_export.h"
 #include "net/disk_cache/blockfile/addr.h"
 
-namespace base {
-class HistogramSamples;
-}  // namespace base
-
 namespace disk_cache {
 
 using StatsItems = base::StringPairs;
 
 // This class stores cache-specific usage information, for tunning purposes.
 class NET_EXPORT_PRIVATE Stats {
  public:
   static const int kDataSizesLength = 28;
   enum Counters {
     MIN_COUNTER = 0,
@@ skipping 63 matching lines @@
   Addr storage_addr_;
   int data_sizes_[kDataSizesLength];
   int64_t counters_[MAX_COUNTER];
 
   DISALLOW_COPY_AND_ASSIGN(Stats);
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_BLOCKFILE_STATS_H_