Add a new QUIC platform API for text utilities.

net/tools/quic/chlo_extractor.cc

Index: net/tools/quic/chlo_extractor.cc
diff --git a/net/tools/quic/chlo_extractor.cc b/net/tools/quic/chlo_extractor.cc
index 3e5ce787f7a4aaa4633704688b995f4acb94dd28..14ac9e300670f2e1c7f3d81deb4dd85278ccd631 100644
--- a/net/tools/quic/chlo_extractor.cc
+++ b/net/tools/quic/chlo_extractor.cc
@@ -4,13 +4,13 @@
 
 #include "net/tools/quic/chlo_extractor.h"
 
-#include "base/strings/string_util.h"
 #include "net/quic/core/crypto/crypto_framer.h"
 #include "net/quic/core/crypto/crypto_handshake_message.h"
 #include "net/quic/core/crypto/crypto_protocol.h"
 #include "net/quic/core/crypto/quic_decrypter.h"
 #include "net/quic/core/crypto/quic_encrypter.h"
 #include "net/quic/core/quic_framer.h"
+#include "net/quic/platform/api/quic_text_utils.h"
 
 using base::StringPiece;
 
@@ -93,7 +93,7 @@ bool ChloFramerVisitor::OnPacketHeader(const QuicPacketHeader& header) {
 bool ChloFramerVisitor::OnStreamFrame(const QuicStreamFrame& frame) {
   StringPiece data(frame.data_buffer, frame.data_length);
   if (frame.stream_id == kCryptoStreamId && frame.offset == 0 &&
-      base::StartsWith(data, "CHLO", base::CompareCase::INSENSITIVE_ASCII)) {
+      QuicTextUtils::StartsWith(data, "CHLO")) {
     CryptoFramer crypto_framer;
     crypto_framer.set_visitor(this);
     if (!crypto_framer.ProcessInput(data)) {