Use installed DBus libraries instead of generating them.

login_manager, power_manager, debugd and shill now expose a client
library with the generated dbus-proxies.h file and the system_api's
installed dbus-constants.h. This patch changes update_engine from
generating these DBus headers to use the installed client libraries.

The client libraries already include the service path string, so we
don't need to include system_api dbus-constants.h in most cases, unless
we actually use some parameter constants defined there.

BUG=b:23084776,b:23560718
TEST=./build_packages --board=link

Change-Id: Idb4501e784ebb5928c92902d114462be57d5826a
diff --git a/shill_proxy.cc b/shill_proxy.cc
index caa68b3..99817ea 100644
--- a/shill_proxy.cc
+++ b/shill_proxy.cc
@@ -16,9 +16,6 @@
 
 #include "update_engine/shill_proxy.h"
 
-#include <chromeos/dbus/service_constants.h>
-
-
 using org::chromium::flimflam::ManagerProxy;
 using org::chromium::flimflam::ManagerProxyInterface;
 using org::chromium::flimflam::ServiceProxy;
@@ -29,10 +26,7 @@
 ShillProxy::ShillProxy(const scoped_refptr<dbus::Bus>& bus) : bus_(bus) {}
 
 bool ShillProxy::Init() {
-  manager_proxy_.reset(
-      new ManagerProxy(bus_,
-                       shill::kFlimflamServiceName,
-                       dbus::ObjectPath(shill::kFlimflamServicePath)));
+  manager_proxy_.reset(new ManagerProxy(bus_));
   return true;
 }
 
@@ -43,8 +37,8 @@
 std::unique_ptr<ServiceProxyInterface> ShillProxy::GetServiceForPath(
     const std::string& path) {
   DCHECK(bus_.get());
-  return std::unique_ptr<ServiceProxyInterface>(new ServiceProxy(
-      bus_, shill::kFlimflamServiceName, dbus::ObjectPath(path)));
+  return std::unique_ptr<ServiceProxyInterface>(
+      new ServiceProxy(bus_, dbus::ObjectPath(path)));
 }
 
 }  // namespace chromeos_update_engine