Delete the ClientSocketPoolHistograms class.

net/http/http_proxy_client_socket_pool.cc

Index: net/http/http_proxy_client_socket_pool.cc
diff --git a/net/http/http_proxy_client_socket_pool.cc b/net/http/http_proxy_client_socket_pool.cc
index 9c8a531778530c6420f9dcd80be1a612baa1ac0f..a861ca479a881ad150d2ce5170f3e2e240fb7372 100644
--- a/net/http/http_proxy_client_socket_pool.cc
+++ b/net/http/http_proxy_client_socket_pool.cc
@@ -440,18 +440,17 @@ HttpProxyClientSocketPool::HttpProxyConnectJobFactory::ConnectionTimeout(
 HttpProxyClientSocketPool::HttpProxyClientSocketPool(
     int max_sockets,
     int max_sockets_per_group,
-    ClientSocketPoolHistograms* histograms,
     TransportClientSocketPool* transport_pool,
     SSLClientSocketPool* ssl_pool,
     NetLog* net_log)
     : transport_pool_(transport_pool),
       ssl_pool_(ssl_pool),
-      base_(this, max_sockets, max_sockets_per_group, histograms,
+      base_(this,
+            max_sockets,
+            max_sockets_per_group,
             ClientSocketPool::unused_idle_socket_timeout(),
             ClientSocketPool::used_idle_socket_timeout(),
-            new HttpProxyConnectJobFactory(transport_pool,
-                                           ssl_pool,
-                                           net_log)) {
+            new HttpProxyConnectJobFactory(transport_pool, ssl_pool, net_log)) {
   // We should always have a |transport_pool_| except in unit tests.
   if (transport_pool_)
     base_.AddLowerLayeredPool(transport_pool_);
@@ -544,10 +543,6 @@ base::TimeDelta HttpProxyClientSocketPool::ConnectionTimeout() const {
   return base_.ConnectionTimeout();
 }
 
-ClientSocketPoolHistograms* HttpProxyClientSocketPool::histograms() const {
-  return base_.histograms();
-}
-
 bool HttpProxyClientSocketPool::IsStalled() const {
   return base_.IsStalled();
 }