Implement the android metrics reporter

Implement the metrics_reporter_android class which reports with
libmetricslogger. We reports the error_code only for now, and more
android metrics will be reported in the following up cls.

Test: mma
Change-Id: Id5760aaa4853fa9ee0248344fa12900b923dfb7f
diff --git a/update_attempter_android.h b/update_attempter_android.h
index 167191e..a347e52 100644
--- a/update_attempter_android.h
+++ b/update_attempter_android.h
@@ -31,6 +31,7 @@
 #include "update_engine/common/hardware_interface.h"
 #include "update_engine/common/prefs_interface.h"
 #include "update_engine/daemon_state_interface.h"
+#include "update_engine/metrics_reporter_interface.h"
 #include "update_engine/network_selector_interface.h"
 #include "update_engine/payload_consumer/download_action.h"
 #include "update_engine/payload_consumer/postinstall_runner_action.h"
@@ -162,6 +163,8 @@
   // before applying an update to the other slot.
   bool updated_boot_flags_ = false;
 
+  std::unique_ptr<MetricsReporterInterface> metrics_reporter_;
+
   DISALLOW_COPY_AND_ASSIGN(UpdateAttempterAndroid);
 };