Add base/parse_number.h to generalize number parsing done in //net.

net/base/sdch_manager.cc

 // Copyright (c) 2012 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/sdch_manager.h"
 
 #include <limits.h>
 
 #include <utility>
 
 #include "base/base64url.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/time/default_clock.h"
 #include "base/values.h"
 #include "crypto/sha2.h"
+#include "net/base/parse_number.h"
 #include "net/base/sdch_observer.h"
 #include "net/url_request/url_request_http_job.h"
 
 namespace {
 
 void StripTrailingDot(GURL* gurl) {
   std::string host(gurl->host());
 
   if (host.empty())
     return;
@@ skipping 340 matching lines @@
       name = base::ToLowerASCII(name);
       if (name == "domain") {
         domain = value;
       } else if (name == "path") {
         path = value;
       } else if (name == "format-version") {
         if (value != "1.0")
           return SDCH_DICTIONARY_UNSUPPORTED_VERSION;
       } else if (name == "max-age") {
         int64_t seconds;
+        // TODO(eroman): crbug.com/596541 -- should not accept a leading +.
         base::StringToInt64(value, &seconds);
         expiration = base::Time::Now() + base::TimeDelta::FromSeconds(seconds);
       } else if (name == "port") {
         int port;
-        base::StringToInt(value, &port);
-        if (port >= 0)
+        if (ParseNonNegativeDecimalInt(value, &port))
           ports.insert(port);
       }
     }
 
     if (line_end >= header_end)
       break;
     line_start = line_end + 1;
   }
 
   // Narrow fix for http://crbug.com/389451.
@@ skipping 78 matching lines @@
       entry_dict->SetInteger("tries", it->second.count);
     entry_dict->SetInteger("reason", it->second.reason);
     entry_list->Append(std::move(entry_dict));
   }
   value->Set("blacklisted", std::move(entry_list));
 
   return std::move(value);
 }
 
 }  // namespace net