Attempting to re-land a small portion of this change... Simply add links from

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 92f0c413ac38628b20ce2ae934359840ba7aa6fe..1c03ecf099d800154d1dd4a988f63465b508b75c 100644
--- a/net/socket/client_socket_pool.h
+++ b/net/socket/client_socket_pool.h
@@ -29,6 +29,17 @@ 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 LayeredPool {
+ public:
+  virtual ~LayeredPool() {};
+
+  // Instructs the LayeredPool to close an idle connection. Return true if one
+  // was closed.
+  virtual bool CloseOneIdleConnection() = 0;
+};
+
 // A ClientSocketPool is used to restrict the number of sockets open at a time.
 // It also maintains a list of idle persistent sockets.
 //
@@ -110,6 +121,10 @@ class NET_EXPORT ClientSocketPool {
   // the pool.  Does not flush any pools wrapped by |this|.
   virtual void Flush() = 0;
 
+  // Returns true if a there is currently a request blocked on the
+  // per-pool (not per-host) max socket limit.
+  virtual bool IsStalled() const = 0;
+
   // Called to close any idle connections held by the connection manager.
   virtual void CloseIdleSockets() = 0;
 
@@ -123,6 +138,12 @@ class NET_EXPORT ClientSocketPool {
   virtual LoadState GetLoadState(const std::string& group_name,
                                  const ClientSocketHandle* handle) const = 0;
 
+  // Adds a LayeredPool on top of |this|.
+  virtual void AddLayeredPool(LayeredPool* layered_pool) = 0;
+
+  // Removes a LayeredPool from |this|.
+  virtual void RemoveLayeredPool(LayeredPool* layered_pool) = 0;
+
   // Retrieves information on the current state of the pool as a
   // DictionaryValue.  Caller takes possession of the returned value.
   // If |include_nested_pools| is true, the states of any nested