Isolates generic DnsClient from AsyncHostResolver.

net/base/dns_util.h

Index: net/base/dns_util.h
diff --git a/net/base/dns_util.h b/net/base/dns_util.h
index f09e9069b0e825545e85371cd80ca5bf2ae44079..c01b2a2942fc6188905fa1456200b2722ac83753 100644
--- a/net/base/dns_util.h
+++ b/net/base/dns_util.h
@@ -19,18 +19,22 @@ namespace net {
 //
 //   dotted: a string in dotted form: "www.google.com"
 //   out: a result in DNS form: "\x03www\x06google\x03com\x00"
-NET_EXPORT_PRIVATE bool DNSDomainFromDot(const std::string& dotted,
+NET_EXPORT_PRIVATE bool DNSDomainFromDot(const base::StringPiece& dotted,
                                          std::string* out);
 
 // DNSDomainToString coverts a domain in DNS format to a dotted string.
-NET_EXPORT_PRIVATE std::string DNSDomainToString(const std::string& domain);
+NET_EXPORT_PRIVATE std::string DNSDomainToString(
+    const base::StringPiece& domain);
 
 // Returns true iff the given character is in the set of valid DNS label
 // characters as given in RFC 3490, 4.1, 3(a)
 NET_EXPORT_PRIVATE bool IsSTD3ASCIIValidCharacter(char c);
 
 // Returns the hostname by trimming the ending dot, if one exists.
-NET_EXPORT std::string TrimEndingDot(const std::string& host);
+NET_EXPORT std::string TrimEndingDot(const base::StringPiece& host);
+
+// TODO(szym): remove all definitions below once DnsRRResolver migrates to
+// DnsClient
 
 // DNS class types.
 static const uint16 kClassIN = 1;