Remove some uses of isdigit in net/, as it can be locale depedent.

net/spdy/spdy_alt_svc_wire_format.cc

 // Copyright (c) 2015 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/spdy/spdy_alt_svc_wire_format.h"
 
 #include <algorithm>
 #include <limits>
 #include <string>
 
 #include "base/logging.h"
+#include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 
 namespace net {
 
 using base::StringPiece;
 
 namespace {
 
 template <class T>
 bool ParsePositiveIntegerImpl(StringPiece::const_iterator c,
                               StringPiece::const_iterator end,
                               T* value) {
   *value = 0;
-  for (; c != end && isdigit(*c); ++c) {
+  // TODO(mmenke):  This really should be using methods in parse_number.h.
+  for (; c != end && '0' <= *c && *c <= '9'; ++c) {
     if (*value > std::numeric_limits<T>::max() / 10) {
       return false;
     }
     *value *= 10;
     if (*value > std::numeric_limits<T>::max() - (*c - '0')) {
       return false;
     }
     *value += *c - '0';
   }
   return (c == end && *value > 0);
@@ skipping 234 matching lines @@
                                          StringPiece::const_iterator end,
                                          std::string* output) {
   output->clear();
   for (; c != end; ++c) {
     if (*c != '%') {
       output->push_back(*c);
       continue;
     }
     DCHECK_EQ('%', *c);
     ++c;
-    if (c == end || !isxdigit(*c)) {
+    if (c == end || !base::IsHexDigit(*c)) {
       return false;
     }
-    char decoded = tolower(*c);
-    // '0' is 0, 'a' is 10.
-    decoded += isdigit(*c) ? (0 - '0') : (10 - 'a');
     // Network byte order is big-endian.
-    decoded <<= 4;
+    int decoded = base::HexDigitToInt(*c) << 4;
+
     ++c;
-    if (c == end || !isxdigit(*c)) {
+    if (c == end || !base::IsHexDigit(*c)) {
       return false;
     }
-    decoded += tolower(*c);
-    // '0' is 0, 'a' is 10.
-    decoded += isdigit(*c) ? (0 - '0') : (10 - 'a');
-    output->push_back(decoded);
+    // Network byte order is big-endian.
+    decoded += base::HexDigitToInt(*c);
+
+    output->push_back(static_cast<char>(decoded));
   }
   return true;
 }
 
 // static
 bool SpdyAltSvcWireFormat::ParseAltAuthority(StringPiece::const_iterator c,
                                              StringPiece::const_iterator end,
                                              std::string* host,
                                              uint16_t* port) {
   host->clear();
@@ skipping 47 matching lines @@
 
 // static
 bool SpdyAltSvcWireFormat::ParsePositiveInteger32(
     StringPiece::const_iterator c,
     StringPiece::const_iterator end,
     uint32_t* value) {
   return ParsePositiveIntegerImpl<uint32_t>(c, end, value);
 }
 
 }  // namespace net