Rename SpdyHeaderBlock to Http2HeaderBlock.

Salvaged from a botched Zwingli attempt:
http://refactor/16032281396283088571 created by go/Zwingli

Tested:
    TAP for global presubmit queue passed after automated deflaking of failures: http://mondo/deflaker/run/ea979a75-dd33-4574-acde-7191db6ea908 http://mondo/deflaker/run/51cec644-aef6-434d-bebd-6cff71dc319b
    http://test/OCL:338336292:BASE:338288991:1603328760683:25591553
PiperOrigin-RevId: 338474585
Change-Id: I3a6fb53e8e3a41386ac9eefc01fb5d32b158d044
diff --git a/quic/tools/quic_simple_server_stream.h b/quic/tools/quic_simple_server_stream.h
index 254fe8d..6b8826c 100644
--- a/quic/tools/quic_simple_server_stream.h
+++ b/quic/tools/quic_simple_server_stream.h
@@ -47,7 +47,7 @@
   // Make this stream start from as if it just finished parsing an incoming
   // request whose headers are equivalent to |push_request_headers|.
   // Doing so will trigger this toy stream to fetch response and send it back.
-  virtual void PushResponse(spdy::SpdyHeaderBlock push_request_headers);
+  virtual void PushResponse(spdy::Http2HeaderBlock push_request_headers);
 
   // The response body of error responses.
   static const char* const kErrorResponseBody;
@@ -76,16 +76,16 @@
   void SendNotFoundResponse();
 
   // Sends the response header and body, but not the fin.
-  void SendIncompleteResponse(spdy::SpdyHeaderBlock response_headers,
+  void SendIncompleteResponse(spdy::Http2HeaderBlock response_headers,
                               absl::string_view body);
 
-  void SendHeadersAndBody(spdy::SpdyHeaderBlock response_headers,
+  void SendHeadersAndBody(spdy::Http2HeaderBlock response_headers,
                           absl::string_view body);
-  void SendHeadersAndBodyAndTrailers(spdy::SpdyHeaderBlock response_headers,
+  void SendHeadersAndBodyAndTrailers(spdy::Http2HeaderBlock response_headers,
                                      absl::string_view body,
-                                     spdy::SpdyHeaderBlock response_trailers);
+                                     spdy::Http2HeaderBlock response_trailers);
 
-  spdy::SpdyHeaderBlock* request_headers() { return &request_headers_; }
+  spdy::Http2HeaderBlock* request_headers() { return &request_headers_; }
 
   const std::string& body() { return body_; }
 
@@ -93,7 +93,7 @@
   void WriteGeneratedBytes();
 
   // The parsed headers received from the client.
-  spdy::SpdyHeaderBlock request_headers_;
+  spdy::Http2HeaderBlock request_headers_;
   int64_t content_length_;
   std::string body_;