Introduce brillo binder interface

This is more or less an exact analogue of the DBus interface, but
available over binder. We also add support to the client library and let
update_engine_client build with binder. We don't yet support an
equivalent of the status signal/the HandleStatusUpdate method. That will
come in a future CL.

Bug: 25908638
TEST=Verified update_engine_client functionality

Change-Id: Ic793619c8019b0d50aa184e0f592b6a9ab71e0b0
diff --git a/daemon.h b/daemon.h
index 31c4bf4..6233064 100644
--- a/daemon.h
+++ b/daemon.h
@@ -20,12 +20,15 @@
 #include <memory>
 #include <string>
 
-#if USE_WEAVE
+#if USE_WEAVE || USE_BINDER
 #include <brillo/binder_watcher.h>
-#endif  // USE_WEAVE
+#endif  // USE_WEAVE || USE_BINDER
 #include <brillo/daemons/daemon.h>
 #include <brillo/dbus/dbus_connection.h>
 
+#if USE_BINDER
+#include "update_engine/binder_service.h"
+#endif  // USE_BINDER
 #include "update_engine/common/subprocess.h"
 #include "update_engine/dbus_service.h"
 #include "update_engine/real_system_state.h"
@@ -54,9 +57,13 @@
   // the main() function.
   Subprocess subprocess_;
 
-#if USE_WEAVE
+#if USE_WEAVE || USE_BINDER
   brillo::BinderWatcher binder_watcher_;
-#endif  // USE_WEAVE
+#endif  // USE_WEAVE || USE_BINDER
+
+#if USE_BINDER
+  android::sp<BinderUpdateEngineService> service_;
+#endif  // USE_BINDER
 
   // The RealSystemState uses the previous classes so it should be defined last.
   std::unique_ptr<RealSystemState> real_system_state_;