Compile apmanager on Android

Noticeable changes to get apmanager to compile on Android:
- Conditional include headers for D-Bus service constants
  based on the target platform.
- Use firewalld proxy instead of permission_broker proxy on
  Android.
- Use stub shill proxy instead of the real one until libshill-client
  is ready.

Bug: 24164800
TEST=Compile apmanager on both Android and Chrome OS
TEST=Run apmanager on Chrome OS device

Change-Id: I7885323796e0043a1e3cc46c129e2736faf4fced
diff --git a/config_unittest.cc b/config_unittest.cc
index 36aed97..bb25c54 100644
--- a/config_unittest.cc
+++ b/config_unittest.cc
@@ -20,10 +20,15 @@
 
 #include <base/strings/string_util.h>
 #include <base/strings/stringprintf.h>
-#include <chromeos/dbus/service_constants.h>
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
+#if !defined(__ANDROID__)
+#include <chromeos/dbus/service_constants.h>
+#else
+#include "dbus/apmanager/dbus-constants.h"
+#endif
+
 #include "apmanager/mock_device.h"
 #include "apmanager/mock_manager.h"