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This removes its subclasses and changes their clients to use
FeaturePromoBubbleView directly.

Change-Id: Ie220ab3b4e7c7653ffefe5b6fc266f76d60b492b
Reviewed-on: https://chromium-review.googlesource.com/c/1298394
Commit-Queue: Collin Baker <collinbaker@chromium.org>
Reviewed-by: Robert Liao <robliao@chromium.org>
Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604125}