Isolates generic DnsClient from AsyncHostResolver.

net/base/dns_util.cc

 // Copyright (c) 2011 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/base/dns_util.h"
 
 #include <cstring>
 
 namespace net {
 
 // Based on DJB's public domain code.
-bool DNSDomainFromDot(const std::string& dotted, std::string* out) {
+bool DNSDomainFromDot(const base::StringPiece& dotted, std::string* out) {
   const char* buf = dotted.data();
   unsigned n = dotted.size();
   char label[63];
   unsigned int labellen = 0; /* <= sizeof label */
   char name[255];
   unsigned int namelen = 0; /* <= sizeof name */
   char ch;
 
   for (;;) {
     if (!n)
@@ skipping 26 matching lines @@
   }
 
   if (namelen + 1 > sizeof name)
     return false;
   name[namelen++] = 0;  // This is the root label (of length 0).
 
   *out = std::string(name, namelen);
   return true;
 }
 
-std::string DNSDomainToString(const std::string& domain) {
+std::string DNSDomainToString(const base::StringPiece& domain) {
   std::string ret;
 
   for (unsigned i = 0; i < domain.size() && domain[i]; i += domain[i] + 1) {
 #if CHAR_MIN < 0
     if (domain[i] < 0)
       return "";
 #endif
     if (domain[i] > 63)
       return "";
 
     if (i)
       ret += ".";
 
     if (static_cast<unsigned>(domain[i]) + i + 1 > domain.size())
       return "";
 
-    ret += domain.substr(i + 1, domain[i]);
+    domain.substr(i + 1, domain[i]).AppendToString(&ret);
   }
   return ret;
 }
 
 bool IsSTD3ASCIIValidCharacter(char c) {
   if (c <= 0x2c)
     return false;
   if (c >= 0x7b)
     return false;
   if (c >= 0x2e && c <= 0x2f)
     return false;
   if (c >= 0x3a && c <= 0x40)
     return false;
   if (c >= 0x5b && c <= 0x60)
     return false;
   return true;
 }
 
-std::string TrimEndingDot(const std::string& host) {
-  std::string host_trimmed = host;
+std::string TrimEndingDot(const base::StringPiece& host) {
+  base::StringPiece host_trimmed = host;
   size_t len = host_trimmed.length();
-  if (len > 1 && host_trimmed[len - 1] == '.')
-    host_trimmed.erase(len - 1);
-  return host_trimmed;
+  if (len > 1 && host_trimmed[len - 1] == '.') {
+    host_trimmed.remove_suffix(1);
+  }
+  return host_trimmed.as_string();
 }
 
 bool DnsResponseBuffer::U8(uint8* v) {
   if (len_ < 1)
     return false;
   *v = *p_;
   p_++;
   len_--;
   return true;
 }
@@ skipping 99 matching lines @@
         break;
     } else {
       return false;
     }
   }
 
   return true;
 }
 
 }  // namespace net