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This CL renames the classes as follows:
* UserActivityLogger -> UserActivityManager
* UserActivityLoggerDelegate -> UserActivityUkmLogger
* UserActivityLoggerDelegateUkm -> UserActivityUkmLoggerImpl
* UserActivityLoggingController -> UserActivityController

Design doc:
https://docs.google.com/document/d/1QXXnRFKiRDvXaxwNTc6djMDC-5e7SXk4i2FI3fpxMdA/edit?usp=sharing

Change-Id: Id8a1b2e35c3bfde9e07ee47613510da5415f038a
Reviewed-on: https://chromium-review.googlesource.com/956164
Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Reviewed-by: Jia Meng <jiameng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542721}