GitLab

Adds a function OverrideTargetDecisionForTesting for
OptimizationGuideKeyedService. Clients can use this to control the
desired prediction outcome in tests.

Bug: 1076075
Change-Id: I56ea2c7c1170c0b305b8f0870e22664460fd0806
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2233300Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Reviewed-by: Michael Crouse <mcrouse@chromium.org>
Commit-Queue: Jia Li <jiakl@google.com>
Cr-Commit-Position: refs/heads/master@{#776327}