Do not try to resolve empty hostnames.

net/proxy/proxy_resolver_v8.cc

 // Copyright (c) 2010 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/proxy/proxy_resolver_v8.h"
 
 #include "base/logging.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 #include "googleurl/src/gurl.h"
@@ skipping 395 matching lines @@
     return UTF8StdStringToV8String(ip_address_list);
   }
 
   // V8 callback for when "dnsResolve()" is invoked by the PAC script.
   static v8::Handle<v8::Value> DnsResolveCallback(const v8::Arguments& args) {
     Context* context =
         static_cast<Context*>(v8::External::Cast(*args.Data())->Value());
 
     // We need at least one string argument.
     std::string hostname;
-    if (!GetHostnameArgument(args, &hostname))
+    if (!GetHostnameArgument(args, &hostname) || hostname.empty())
       return v8::Null();
 
     std::string ip_address;
     bool success;
 
     {
       v8::Unlocker unlocker;
 
       LogEventToCurrentRequest(context,
                                NetLog::PHASE_BEGIN,
@@ skipping 121 matching lines @@
 
   // Try parsing the PAC script.
   scoped_ptr<Context> context(new Context(js_bindings_.get()));
   int rv = context->InitV8(bytes_utf8);
   if (rv == OK)
     context_.reset(context.release());
   return rv;
 }
 
 }  // namespace net