Moves QuicTag typedefs, and QuicTag utility methods to quic_tag.{h,cc}. No behavior change.

net/quic/core/quic_tag_test.cc

Index: net/quic/core/quic_tag_test.cc
diff --git a/net/quic/core/quic_tag_test.cc b/net/quic/core/quic_tag_test.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6b1cdd74d3e18f00baae612167e3fbaa1d510645
--- /dev/null
+++ b/net/quic/core/quic_tag_test.cc
@@ -0,0 +1,27 @@
+// Copyright (c) 2016 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.
+
+#include "net/quic/core/quic_tag.h"
+
+#include "net/quic/core/crypto/crypto_protocol.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+namespace test {
+namespace {
+
+TEST(QuicTagTest, TagToString) {
+  EXPECT_EQ("SCFG", QuicTagToString(kSCFG));
+  EXPECT_EQ("SNO ", QuicTagToString(kServerNonceTag));
+  EXPECT_EQ("CRT ", QuicTagToString(kCertificateTag));
+  EXPECT_EQ("CHLO", QuicTagToString(MakeQuicTag('C', 'H', 'L', 'O')));
+  // A tag that contains a non-printing character will be printed as a decimal
+  // number.
+  EXPECT_EQ("525092931", QuicTagToString(MakeQuicTag('C', 'H', 'L', '\x1f')));
+}
+
+}  // namespace
+}  // namespace test
+}  // namespace net