Break up matchesSimple into helper functions.

Add getStartEndAtDepth() for mapping start and end indices at the
specified depth.
Add computeRanges() for computing set of start and end indices in
vector<FieldValue> for matching.

Bug: 316980905
Test: statsd_test
Change-Id: Ifa0f0da50d6ce81830d061c188d58510e72df681
1 file changed