Delete the ClientSocketPoolHistograms class.

net/socket/client_socket_pool.h

Index: net/socket/client_socket_pool.h
diff --git a/net/socket/client_socket_pool.h b/net/socket/client_socket_pool.h
index 2a2be36c8cdaabf7ec674f4a18823302e5b16527..5404db6b59f66b22644706bd339e2b5362bfe1d6 100644
--- a/net/socket/client_socket_pool.h
+++ b/net/socket/client_socket_pool.h
@@ -26,7 +26,6 @@ class DictionaryValue;
 namespace net {
 
 class ClientSocketHandle;
-class ClientSocketPoolHistograms;
 class StreamSocket;
 
 // ClientSocketPools are layered. This defines an interface for lower level
@@ -170,10 +169,6 @@ class NET_EXPORT ClientSocketPool : public LowerLayeredPool {
   // 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);