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- Setup prefetch notification service, factory and client code.

Bug: 1047037
Change-Id: Iccc82d8b49f63213294eb0440fc59138db756912
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2029293
Commit-Queue: Hesen Zhang <hesen@chromium.org>
Auto-Submit: Hesen Zhang <hesen@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Reviewed-by: Xing Liu <xingliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738697}