Avoid SpdyHeaderBlock copy in SpdyStream::OnPushPromiseHeadersReceived().

net/spdy/spdy_stream.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_SPDY_SPDY_STREAM_H_
 #define NET_SPDY_SPDY_STREAM_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 290 matching lines @@
 
   // Called by the SpdySession (only after
   // OnInitialResponseHeadersReceived() has been called) when
   // late-bound headers are received for a stream. Returns a status
   // code; if it is an error, the stream was closed by this function.
   int OnAdditionalResponseHeadersReceived(
       const SpdyHeaderBlock& additional_response_headers);
 
   // Called by the SpdySession when a frame carrying request headers opening a
   // push stream is received. Stream transits to STATE_RESERVED_REMOTE state.
-  void OnPushPromiseHeadersReceived(const SpdyHeaderBlock& headers);
+  void OnPushPromiseHeadersReceived(SpdyHeaderBlock headers);
 
   // Called by the SpdySession when response data has been received
   // for this stream.  This callback may be called multiple times as
   // data arrives from the network, and will never be called prior to
   // OnResponseHeadersReceived.
   //
   // |buffer| contains the data received, or NULL if the stream is
   //          being closed.  The stream must copy any data from this
   //          buffer before returning from this callback.
   //
@@ skipping 245 matching lines @@
   bool write_handler_guard_;
 
   base::WeakPtrFactory<SpdyStream> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SpdyStream);
 };
 
 }  // namespace net
 
 #endif  // NET_SPDY_SPDY_STREAM_H_