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Add the class FullRestoreDataHandler to observe AppRegistryCache. When
the app is removed, remove the full restore data from both
FullRestoreReadHandler and FullRestoreSaveHandler.

BUG=1146900

Change-Id: Ie55b6310e3e302ac4829b7c76c10880928266651
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2608045
Commit-Queue: Nancy Wang <nancylingwang@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#841611}