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This is a follow up CL for https://crrev.com/c/2359749. It is for
pure refactoring.

The plan for this two-sided patch is:
1) Add the new class under feedback/ and AppHooks method upstream with
no reference.
2) Extend the new class downstream and add the new AppHooks method.
3) Update upstream references to point to the new AppHooks method.
4) Cleanup.

This CL is for step 1). Step 2) will be done in
https://crrev.com/i/3227761 once this CL is landed.

Bug: 1117343
Change-Id: I312f3459360fa5e1b78f6e301b052a36bed2e9b4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2364581Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Reviewed-by: Natalie Chouinard <chouinard@chromium.org>
Commit-Queue: Xinghui Lu <xinghuilu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#803360}