chromium_tests: extract get_bot_config
chromium_tests: extract get_bot_config

BUG=418185

Review URL: https://codereview.chromium.org/1289253002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@296313 0039d316-1c4b-4281-b951-d872f2087c98

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