Add ClearControlFrame() to quic_test_utils.

This function does not have to live in a class and does not need seven identical
definitions.

gfe-relnote: n/a, test-only refactoring.
PiperOrigin-RevId: 254999491
Change-Id: I1173acb47388e3a5ca010c927c4e886d3b6ab387
diff --git a/quic/test_tools/quic_test_utils.h b/quic/test_tools/quic_test_utils.h
index 4acc275..85611d0 100644
--- a/quic/test_tools/quic_test_utils.h
+++ b/quic/test_tools/quic_test_utils.h
@@ -208,6 +208,9 @@
 // Compute SHA-1 hash of the supplied std::string.
 std::string Sha1Hash(QuicStringPiece data);
 
+// Delete |frame| and return true.
+bool ClearControlFrame(const QuicFrame& frame);
+
 // Simple random number generator used to compute random numbers suitable
 // for pseudo-randomly dropping packets in tests.
 class SimpleRandom : public QuicRandom {