Deprecate Activation computing delay histograms

Since we started speculatively computing activation state, this histogram
is mostly tracking 0us, 99.97-99.99% of the time.

Bug: 975038
Change-Id: I9087636fd0ccfa942c0f2023aa7a106608458d33
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1685814
Commit-Queue: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: John Delaney <johnidel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#674225}
4 files changed