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- Moves IsMetricsReportingForceEnabled to the base class,
  so that leaf clients don't have to override it.
- Removes CreateEntropyProvider() wrapper in favor of
  GetMetricsStateManager() which was already implemented
  by both clients.
- Reorders functions.
- Removes unnecessary .get() calls.

No functional changes.

TBR=olivierrobin@chromium.org

Bug: None
Change-Id: Ia6666d8c82c394a01bf4fb3980603ddf86335c17
Reviewed-on: https://chromium-review.googlesource.com/c/1391783
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619653}