shill: track wpa_supplicant state, and use it
to update Service state

BUG=chromium-os:22594
TEST=unittests, manual

Manual testing: tried network_WiFiRoaming.002Suspend,
but this still fails. The reason is that we ignore
transitions into disconnected state. I'll address that
in a separate patch, which will add tracking of
CurrentBSS.

Bonus changes bundled in this commit:
- fix some comments (capitalization/punctuation,
  XXX -> TODO)
- WiFiMainTest::InitateConnect arg changed from bare pointer
  to refptr

Change-Id: I6c42f9794c8742fa2b46d03a54d77e0545c899c5
Reviewed-on: https://gerrit.chromium.org/gerrit/11460
Reviewed-by: Gaurav Shah <gauravsh@chromium.org>
Commit-Ready: mukesh agrawal <quiche@chromium.org>
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Tested-by: mukesh agrawal <quiche@chromium.org>
diff --git a/supplicant_interface_proxy.cc b/supplicant_interface_proxy.cc
index ebc5db0..6d80432 100644
--- a/supplicant_interface_proxy.cc
+++ b/supplicant_interface_proxy.cc
@@ -100,9 +100,9 @@
 }
 
 void SupplicantInterfaceProxy::Proxy::PropertiesChanged(
-    const std::map<string, ::DBus::Variant> &/*properties*/) {
+    const std::map<string, ::DBus::Variant> &properties) {
   LOG(INFO) << __func__;
-  // XXX
+  wifi_->PropertiesChanged(properties);
 }
 
 void SupplicantInterfaceProxy::Proxy::ScanDone(const bool& success) {