bot_scaling: Add lookback_hours for BotPolicy

Add a field to set the lookback number of hours for querying Swarming
stats.  This will allow the ability to set the size of the lookback
window when determining the start time for tasks.  Swarming querying
will only return tasks that have started within the lookback window,
therefore we need to support longer windows than the currently default
24 hours.

Bug: chromium:1027593
Change-Id: I631384d840bd88ea81bc1a15c1142ca4c1838d3c
Commit-Queue: Mike Nichols <>
Tested-by: Mike Nichols <>
Reviewed-by: David Burger <>
Reviewed-by: Sean Abraham <>
2 files changed