Add a document explaining how to create a data studio dashboard using
the repo diff tool.
Renamed repo_diff_downstream.py to repo_diff_trees.py.
Renamed exclusions.txt to android_exclusions.txt.
Not all Android source trees support build IDs and tags.
When no build tag is requested, rather than try to match
the build IDs just sync the branch tips of the upstream
and downstream source trees.
Also select two Android Oreo release candidates
as the default branches. The fact that there are frozen
branches and that the diff is small serve as a good showcase
of the tool.
Change-Id: Ifdefd79fb6b32c6b83e0aee390dd5a435b6a61fc
These tools help compare android repo workspaces for high level
analysis.
Test: Run python repo_diff/repo_diff_android.py
Change-Id: I645351521c7f61735d3ce65a93569983cd28851c
