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Feed component adds a significant amount of code that's not used yet
for users. See Feed DEPS rolls for current size impact.

This change also fixes some areas outside of components/feed/ that were
assuming Feed was always compiled in on Android.

TBR=gab@chromium.org

Change-Id: I72944b4518388ee650f9fd0c444d52b9ddcc23b7
Reviewed-on: https://chromium-review.googlesource.com/1142296
Commit-Queue: Sky Malice <skym@chromium.org>
Reviewed-by: Filip Gorski <fgorski@chromium.org>
Reviewed-by: Martin Šrámek <msramek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576351}