Add a mechanism to disable IPv6....

net/base/host_cache.cc

Index: net/base/host_cache.cc
===================================================================
--- net/base/host_cache.cc	(revision 29420)
+++ net/base/host_cache.cc	(working copy)
@@ -29,12 +29,12 @@
 HostCache::~HostCache() {
 }
 
-const HostCache::Entry* HostCache::Lookup(const std::string& hostname,
+const HostCache::Entry* HostCache::Lookup(const Key& key,
                                           base::TimeTicks now) const {
   if (caching_is_disabled())
     return NULL;
 
-  EntryMap::const_iterator it = entries_.find(hostname);
+  EntryMap::const_iterator it = entries_.find(key);
   if (it == entries_.end())
     return NULL;  // Not found.
 
@@ -45,7 +45,7 @@
   return NULL;
 }
 
-HostCache::Entry* HostCache::Set(const std::string& hostname,
+HostCache::Entry* HostCache::Set(const Key& key,
                                  int error,
                                  const AddressList addrlist,
                                  base::TimeTicks now) {
@@ -55,7 +55,7 @@
   base::TimeTicks expiration = now +
       base::TimeDelta::FromMilliseconds(cache_duration_ms_);
 
-  scoped_refptr<Entry>& entry = entries_[hostname];
+  scoped_refptr<Entry>& entry = entries_[key];
   if (!entry) {
     // Entry didn't exist, creating one now.
     Entry* ptr = new Entry(error, addrlist, expiration);