Bug: 22817899 Change-Id: I900f19cca54daabd45fe358ae4117d4f3e9ab824
Bug: 23591361 Bug: 26688835 Change-Id: If1039356468d173522132df252e81807cdc756c8
First of several change lists: 1. Add in the new proto (this CL) 2. Migrate the existing code over to the proto. 3. Remove MetricsConstants once it is unused. Bug: 26442178 Change-Id: Ic24829246af8ec5b202e39a85960aac5cf336c33