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When the feature is turned on, replaces the two screenshot related tools
in the palette bubble. This uses the existing palette tool histogram
recording. Removes some unused functions. Screenshot in linked bug.

Test: manual
Change-Id: I145dd875fac579955b17531c63b5bed2d2e48305
Fixed: 1113014
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2333824
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795211}