Extract generic capacity estimation function from estimate_capacity.py
Extract generic capacity estimation function from estimate_capacity.py

This is a preparation to estimating swarming capacity needs.

BUG=431479

Review URL: https://codereview.chromium.org/1014343002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@294487 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build