Move logic to figure out if a socket can be reused into HttpStream.

net/http/http_stream_parser.h

Index: net/http/http_stream_parser.h
diff --git a/net/http/http_stream_parser.h b/net/http/http_stream_parser.h
index 471d9f10c39ba9c5e04dc3268af2c7fc8d8e2a40..cb18cc81cf2e3f74b0b4336bdbbd4b397da5bf05 100644
--- a/net/http/http_stream_parser.h
+++ b/net/http/http_stream_parser.h
@@ -73,7 +73,15 @@ class NET_EXPORT_PRIVATE HttpStreamParser {
 
   void SetConnectionReused();
 
-  bool IsConnectionReusable() const;
+  // Returns true if the underlying connection can be reused.
+  // The connection can be reused if:
+  // * It's still connected.
+  // * The response headers indicate the connection can be kept alive.
+  // * The end of the response can be found.
+  //
+  // Note that if response headers have yet to be received, this will return
+  // false.
+  bool CanReuseConnection() const;
 
   int64 received_bytes() const { return received_bytes_; }