Replace QuicString with std::string, pass 1

This replaces QuicString with std::string in all of the "QUIC proper".  I will
delete QuicString once all code using it is gone.

gfe-relnote: n/a (no functional change)
PiperOrigin-RevId: 237872023
Change-Id: I82de62c9855516b15039734d05155917e68ff4ee
diff --git a/quic/core/crypto/cert_compressor_test.cc b/quic/core/crypto/cert_compressor_test.cc
index 87b330a..e3ac2f1 100644
--- a/quic/core/crypto/cert_compressor_test.cc
+++ b/quic/core/crypto/cert_compressor_test.cc
@@ -18,26 +18,26 @@
 class CertCompressorTest : public QuicTest {};
 
 TEST_F(CertCompressorTest, EmptyChain) {
-  std::vector<QuicString> chain;
-  const QuicString compressed = CertCompressor::CompressChain(
+  std::vector<std::string> chain;
+  const std::string compressed = CertCompressor::CompressChain(
       chain, QuicStringPiece(), QuicStringPiece(), nullptr);
   EXPECT_EQ("00", QuicTextUtils::HexEncode(compressed));
 
-  std::vector<QuicString> chain2, cached_certs;
+  std::vector<std::string> chain2, cached_certs;
   ASSERT_TRUE(CertCompressor::DecompressChain(compressed, cached_certs, nullptr,
                                               &chain2));
   EXPECT_EQ(chain.size(), chain2.size());
 }
 
 TEST_F(CertCompressorTest, Compressed) {
-  std::vector<QuicString> chain;
+  std::vector<std::string> chain;
   chain.push_back("testcert");
-  const QuicString compressed = CertCompressor::CompressChain(
+  const std::string compressed = CertCompressor::CompressChain(
       chain, QuicStringPiece(), QuicStringPiece(), nullptr);
   ASSERT_GE(compressed.size(), 2u);
   EXPECT_EQ("0100", QuicTextUtils::HexEncode(compressed.substr(0, 2)));
 
-  std::vector<QuicString> chain2, cached_certs;
+  std::vector<std::string> chain2, cached_certs;
   ASSERT_TRUE(CertCompressor::DecompressChain(compressed, cached_certs, nullptr,
                                               &chain2));
   EXPECT_EQ(chain.size(), chain2.size());
@@ -45,12 +45,12 @@
 }
 
 TEST_F(CertCompressorTest, Common) {
-  std::vector<QuicString> chain;
+  std::vector<std::string> chain;
   chain.push_back("testcert");
   static const uint64_t set_hash = 42;
   std::unique_ptr<CommonCertSets> common_sets(
       crypto_test_utils::MockCommonCertSets(chain[0], set_hash, 1));
-  const QuicString compressed = CertCompressor::CompressChain(
+  const std::string compressed = CertCompressor::CompressChain(
       chain,
       QuicStringPiece(reinterpret_cast<const char*>(&set_hash),
                       sizeof(set_hash)),
@@ -62,7 +62,7 @@
       "00" /* end of list */,
       QuicTextUtils::HexEncode(compressed));
 
-  std::vector<QuicString> chain2, cached_certs;
+  std::vector<std::string> chain2, cached_certs;
   ASSERT_TRUE(CertCompressor::DecompressChain(compressed, cached_certs,
                                               common_sets.get(), &chain2));
   EXPECT_EQ(chain.size(), chain2.size());
@@ -70,18 +70,18 @@
 }
 
 TEST_F(CertCompressorTest, Cached) {
-  std::vector<QuicString> chain;
+  std::vector<std::string> chain;
   chain.push_back("testcert");
   uint64_t hash = QuicUtils::FNV1a_64_Hash(chain[0]);
   QuicStringPiece hash_bytes(reinterpret_cast<char*>(&hash), sizeof(hash));
-  const QuicString compressed = CertCompressor::CompressChain(
+  const std::string compressed = CertCompressor::CompressChain(
       chain, QuicStringPiece(), hash_bytes, nullptr);
 
   EXPECT_EQ("02" /* cached */ + QuicTextUtils::HexEncode(hash_bytes) +
                 "00" /* end of list */,
             QuicTextUtils::HexEncode(compressed));
 
-  std::vector<QuicString> cached_certs, chain2;
+  std::vector<std::string> cached_certs, chain2;
   cached_certs.push_back(chain[0]);
   ASSERT_TRUE(CertCompressor::DecompressChain(compressed, cached_certs, nullptr,
                                               &chain2));
@@ -90,7 +90,7 @@
 }
 
 TEST_F(CertCompressorTest, BadInputs) {
-  std::vector<QuicString> cached_certs, chain;
+  std::vector<std::string> cached_certs, chain;
 
   EXPECT_FALSE(CertCompressor::DecompressChain(
       QuicTextUtils::HexEncode("04") /* bad entry type */, cached_certs,