net: fix leak in SSLHostInfo's DNS request.

I'm too used to callbacks which delete themselves and forgot to delete
it myself in r70631.

BUG=68820
TEST=valgrind

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@70737 0039d316-1c4b-4281-b951-d872f2087c98

net/socket/ssl_host_info.cc

@@ -220,6 +220,7 @@ void SSLHostInfo::VerifyCallback(int rv) {
 
 void SSLHostInfo::DnsComplete(int rv) {
   dns_handle_ = DnsRRResolver::kInvalidHandle;
+  delete dns_callback_;
   dns_callback_ = NULL;
 
   const base::TimeTicks now = base::TimeTicks::Now();