Update to use libbrillo Chrome proxy resolver

This uses the new proxy resolution code in libbrillo for doing proxy
resolution rather than making the D-Bus calls directly through the
generated bindings. The unittest for this class was removed since the
main function of it was removed. It now is essentially just a wrapper
around the call into libbrillo along with some minimal code for
allowing cancelling of callbacks.

BUG=chromium:771386
TEST=Unit tests pass

Change-Id: Ib0d4e413482f4bdfe0e9689f68118efbec94ec9d
Reviewed-on: https://chromium-review.googlesource.com/698964
Commit-Ready: Jeffrey Kardatzke <jkardatzke@google.com>
Tested-by: Jeffrey Kardatzke <jkardatzke@google.com>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Jeffrey Kardatzke <jkardatzke@google.com>
Reviewed-by: Sen Jiang <senj@chromium.org>
diff --git a/update_attempter.cc b/update_attempter.cc
index 136413d..9b34365 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -122,17 +122,10 @@
 
 UpdateAttempter::UpdateAttempter(
     SystemState* system_state,
-    CertificateChecker* cert_checker,
-    org::chromium::NetworkProxyServiceInterfaceProxyInterface*
-        network_proxy_service_proxy)
+    CertificateChecker* cert_checker)
     : processor_(new ActionProcessor()),
       system_state_(system_state),
-#if USE_CHROME_NETWORK_PROXY
-      cert_checker_(cert_checker),
-      chrome_proxy_resolver_(network_proxy_service_proxy) {
-#else
       cert_checker_(cert_checker) {
-#endif  // USE_CHROME_NETWORK_PROXY
 }
 
 UpdateAttempter::~UpdateAttempter() {