Add a new SpdyStream::Delegate method to handle trailers

net/spdy/spdy_stream.h

Index: net/spdy/spdy_stream.h
diff --git a/net/spdy/spdy_stream.h b/net/spdy/spdy_stream.h
index 4c01e0cecef2c2234fdf9eea32b4a8a4fe4a1c93..e339f7c61c25e78275c9392f208b76a046dae7f0 100644
--- a/net/spdy/spdy_stream.h
+++ b/net/spdy/spdy_stream.h
@@ -57,7 +57,8 @@ enum SpdySendStatus {
 // whether the current response headers are complete or not.
 enum SpdyResponseHeadersStatus {
   RESPONSE_HEADERS_ARE_INCOMPLETE,
-  RESPONSE_HEADERS_ARE_COMPLETE
+  RESPONSE_HEADERS_ARE_COMPLETE,
+  TRAILERS_RECEIVED,
 };
 
 // The SpdyStream is used by the SpdySession to represent each stream known
@@ -148,6 +149,11 @@ class NET_EXPORT_PRIVATE SpdyStream {
     // handle it gracefully.
     virtual void OnClose(int status) = 0;
 
+    // Called when trailers are received. Note that trailers HEADER frame will
+    // have END_STREAM flag set, so this will be followed by OnDataReceived with

[xunjieli, 2015/08/06 21:02:00]

Sorry this comment isn't quite right. SpdyStream::OnDataReceived will be invoked
with an empty buffer, but SpdyStream::Delegate::OnDataReceived won't be invoked.
I updated it and also moved the method above OnClose to match the execution
flow.

+    // an empty buffer.
+    virtual void OnTrailers(const SpdyHeaderBlock& trailers);
+
    protected:
     virtual ~Delegate() {}