Add more tracing for obtainStyledAttributes

Much of the time for View inflation is spent in calls to
obtainStyledAttributes. This change adds more granular tracing of this method so
we can better attribute how inflation time is spent.

Test: manual - looked at systrace for starting an app.

Change-Id: Ib72aef1e8b788ce5a61ba13b57bb4417a263b48c