shill: Connection: Don't call Resolver::SetDNSFromIPConfig

Don't ever call this function (in fact, remove this from the
resolver), and refactor the code that correctly generates the
DNS search list so that it is usable both from
Connection::UpdateFromIPConfig() and from void
Connection::SetIsDefault().

BUG=chromium-os:34260
TEST=Rerun unit tests + Manual: Connect to AP that supplies only
"DomainName", and ensure that /etc/resolv.conf contains this domain
in the search field both initially and after DHCP renewal.

Change-Id: I9a0705cb54e6588915533cc343b05efcdee71293
Reviewed-on: https://gerrit.chromium.org/gerrit/32996
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Commit-Ready: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
diff --git a/resolver.h b/resolver.h
index 8c56712..2aeb4a7 100644
--- a/resolver.h
+++ b/resolver.h
@@ -36,11 +36,9 @@
 
   virtual void set_path(const FilePath &path) { path_ = path; }
 
-  // Set the default domain name service parameters, given an ipconfig entry.
-  virtual bool SetDNSFromIPConfig(const IPConfigRefPtr &ipconfig,
-                                  TimeoutParameters timeout);
-
-  // Set the default domain name service parameters, given an ipconfig entry.
+  // Install domain name service parameters, given a list of
+  // DNS servers in |dns_servers|, a list of DNS search suffixes in
+  // |domain_search| and a DNS timeout parameter in |timeout|.
   virtual bool SetDNSFromLists(const std::vector<std::string> &dns_servers,
                                const std::vector<std::string> &domain_search,
                                TimeoutParameters timeout);