Slow start pipelining.

net/http/http_pipelined_host_pool.h

Index: net/http/http_pipelined_host_pool.h
diff --git a/net/http/http_pipelined_host_pool.h b/net/http/http_pipelined_host_pool.h
index 5e7c146efd76e93d07e9119e3ecd27d514c3cdcc..3be0cb51e9eb4d56ebabc012c8efebd764b20bb7 100644
--- a/net/http/http_pipelined_host_pool.h
+++ b/net/http/http_pipelined_host_pool.h
@@ -9,21 +9,37 @@
 #include <map>
 
 #include "base/basictypes.h"
+#include "base/gtest_prod_util.h"
+#include "base/memory/mru_cache.h"
+#include "base/memory/scoped_ptr.h"
 #include "net/http/http_pipelined_host.h"
 
 namespace net {
 
 class HostPortPair;
 class HttpPipelinedStream;
-class HttpStreamFactoryImpl;
 
 // Manages all of the pipelining state for specific host with active pipelined
 // HTTP requests. Manages connection jobs, constructs pipelined streams, and
 // assigns requests to the least loaded pipelined connection.
-class HttpPipelinedHostPool : public HttpPipelinedHost::Delegate {
+class NET_EXPORT_PRIVATE HttpPipelinedHostPool
+    : public HttpPipelinedHost::Delegate {
  public:
-  explicit HttpPipelinedHostPool(HttpStreamFactoryImpl* factory);
-  ~HttpPipelinedHostPool();
+  class Delegate {
+   public:
+    // Called when a HttpPipelinedHost has new capacity. Attempts to allocate
+    // any pending pipeline-capable requests to pipelines.
+    virtual void OnHttpPipelinedHostHasAdditionalCapacity(
+        const HostPortPair& origin) = 0;
+  };
+
+  HttpPipelinedHostPool(Delegate* delegate,
+                        HttpPipelinedHost::Factory* factory);
+  virtual ~HttpPipelinedHostPool();
+
+  // Returns true if pipelining might work for |origin|. Generally, this returns
+  // true, unless |origin| is known to have failed pipelining recently.
+  bool IsHostEligibleForPipelining(const HostPortPair& origin);
 
   // Constructs a new pipeline on |connection| and returns a new
   // HttpPipelinedStream that uses it.
@@ -49,14 +65,24 @@ class HttpPipelinedHostPool : public HttpPipelinedHost::Delegate {
 
   virtual void OnHostHasAdditionalCapacity(HttpPipelinedHost* host) OVERRIDE;
 
+  virtual void OnHostDeterminedCapability(
+      HttpPipelinedHost* host,
+      HttpPipelinedHost::Capability capability) OVERRIDE;
+
  private:
+  typedef base::MRUCache<HostPortPair,
+                         HttpPipelinedHost::Capability> CapabilityMap;
   typedef std::map<const HostPortPair, HttpPipelinedHost*> HostMap;
 
   HttpPipelinedHost* GetPipelinedHost(const HostPortPair& origin,
                                       bool create_if_not_found);
 
-  HttpStreamFactoryImpl* factory_;
+  HttpPipelinedHost::Capability GetHostCapability(const HostPortPair& origin);
+
+  Delegate* delegate_;
+  scoped_ptr<HttpPipelinedHost::Factory> factory_;
   HostMap host_map_;
+  CapabilityMap known_capability_map_;
 
   DISALLOW_COPY_AND_ASSIGN(HttpPipelinedHostPool);
 };