common: Split out metrics utils from utils.cc.

The utility functions to convert error codes and network settings to
the types defined by the metrics framework are split out the utils.cc
file. These tools are only used by the update_engine daemon to report
back metrics on an update check.

Bug: 25197634
Test: FEATURES=test emerge-link update_engine; mma

Change-Id: I589dc9f6056fb1399fa84ca4f44076ed3a6b5365
diff --git a/Android.mk b/Android.mk
index 9b6e771..29afd3c 100644
--- a/Android.mk
+++ b/Android.mk
@@ -256,6 +256,7 @@
     image_properties_android.cc \
     libcros_proxy.cc \
     metrics.cc \
+    metrics_utils.cc \
     omaha_request_action.cc \
     omaha_request_params.cc \
     omaha_response_handler_action.cc \