Delete the ClientSocketPoolHistograms class.

net/socket/client_socket_pool.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_SOCKET_CLIENT_SOCKET_POOL_H_
 #define NET_SOCKET_CLIENT_SOCKET_POOL_H_
 
 #include <deque>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/template_util.h"
 #include "base/time/time.h"
 #include "net/base/completion_callback.h"
 #include "net/base/load_states.h"
 #include "net/base/net_export.h"
 #include "net/base/request_priority.h"
 #include "net/dns/host_resolver.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 namespace net {
 
 class ClientSocketHandle;
-class ClientSocketPoolHistograms;
 class StreamSocket;
 
 // ClientSocketPools are layered. This defines an interface for lower level
 // socket pools to communicate with higher layer pools.
 class NET_EXPORT HigherLayeredPool {
  public:
   virtual ~HigherLayeredPool() {}
 
   // Instructs the HigherLayeredPool to close an idle connection. Return true if
   // one was closed.  Closing an idle connection will call into the lower layer
@@ skipping 123 matching lines @@
   // If |include_nested_pools| is true, the states of any nested
   // ClientSocketPools will be included.
   virtual base::DictionaryValue* GetInfoAsValue(
       const std::string& name,
       const std::string& type,
       bool include_nested_pools) const = 0;
 
   // Returns the maximum amount of time to wait before retrying a connect.
   static const int kMaxConnectRetryIntervalMs = 250;
 
-  // The set of histograms specific to this pool.  We can't use the standard
-  // UMA_HISTOGRAM_* macros because they are callsite static.
-  virtual ClientSocketPoolHistograms* histograms() const = 0;
-
   static base::TimeDelta unused_idle_socket_timeout();
   static void set_unused_idle_socket_timeout(base::TimeDelta timeout);
 
   static base::TimeDelta used_idle_socket_timeout();
   static void set_used_idle_socket_timeout(base::TimeDelta timeout);
 
  protected:
   ClientSocketPool();
   ~ClientSocketPool() override;
 
@@ skipping 10 matching lines @@
     const std::string& group_name,
     const scoped_refptr<typename PoolType::SocketParams>& params,
     int num_sockets,
     const BoundNetLog& net_log) {
   pool->RequestSockets(group_name, &params, num_sockets, net_log);
 }
 
 }  // namespace net
 
 #endif  // NET_SOCKET_CLIENT_SOCKET_POOL_H_