[Feed] Import feed@4dedff6189bbd8f3dc594ba3e2159ccdf929359a

This patch rolls the Feed library forward to revision:
4dedff6189bbd8f3dc594ba3e2159ccdf929359a

This patch also fixes the BUILD.gn:
* adds missing files.
* reduces the number of targets, to simplify management.

Because none of the code is presently used, it has no impact on
DEX sizes. There is a minor impact on resources size (1kB).

Change-Id: Idcd00ea084c137f2b9d9f4bf46ea1051930b1b0c
Reviewed-on: https://chromium-review.googlesource.com/952185
Reviewed-by: agrieve <[email protected]>
Reviewed-by: Pavel Yatsuk <[email protected]>
Commit-Queue: Filip Gorski <[email protected]>
Cr-Commit-Position: refs/heads/master@{#541548}
3 files changed