Replace the existing SpdyHeaderBlock typedef with a class.

net/spdy/spdy_test_utils.h

Index: net/spdy/spdy_test_utils.h
diff --git a/net/spdy/spdy_test_utils.h b/net/spdy/spdy_test_utils.h
index ee3d6582fb86c0318abd2042098d180f0971bdc2..e052a3f0dc3e1fb05661c5e26217edcb5ef43ff4 100644
--- a/net/spdy/spdy_test_utils.h
+++ b/net/spdy/spdy_test_utils.h
@@ -9,6 +9,7 @@
 
 #include <string>
 
+#include "net/spdy/spdy_header_block.h"
 #include "net/spdy/spdy_protocol.h"
 
 namespace net {
@@ -16,6 +17,11 @@ namespace net {
 class HashValue;
 class TransportSecurityState;
 
+inline bool operator==(StringPiece x,
+                       const SpdyHeaderBlock::StringPieceProxy& y) {
+  return x == y.operator StringPiece();
+}
+
 namespace test {
 
 std::string HexDumpWithMarks(const unsigned char* data, int length,