Release SpdySession socket read buffer

net/spdy/spdy_session.h

Index: net/spdy/spdy_session.h
diff --git a/net/spdy/spdy_session.h b/net/spdy/spdy_session.h
index 00564823aa117f8b8cbf97912381b9fa9da4e54d..9852e2d6e33b2b7b579520b84204c43aa8bab03b 100644
--- a/net/spdy/spdy_session.h
+++ b/net/spdy/spdy_session.h
@@ -1019,6 +1019,7 @@ class NET_EXPORT SpdySession : public BufferedSpdyFramerVisitorInterface,
   std::unique_ptr<ClientSocketHandle> connection_;
 
   // The read buffer used to read data from the socket.
+  // Non-null if there is a Read() pending.
   scoped_refptr<IOBuffer> read_buffer_;
 
   SpdyStreamId stream_hi_water_mark_;  // The next stream id to use.