Reland "[vr] Update assets component when entering VR and component not ready"

This is a reland of 8a2c2f916eb0391802d9f4d37be2651d67956f85
Original change's description:
> [vr] Update assets component when entering VR and component not ready
>
> We need the assets component in VR browsing mode to provide the best
> user experience. Thus, initiate an immediate update check when entering
> VR and no compatible component is available in order to minimize the
> time the user has to browse in the fallback browsing mode.
>
> Bug: 793975
> Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
> Change-Id: I7a74173807e76a457c0f8c7bfed7384596c90e35
> Reviewed-on: https://chromium-review.googlesource.com/850852
> Commit-Queue: Tibor Goldschwendt <[email protected]>
> Reviewed-by: Ian Vollick <[email protected]>
> Reviewed-by: Joshua Pawlicki <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#527338}

[email protected],[email protected]

Bug: 793975
Change-Id: Idf04fe94ae635655bf300b874b779842b1419eac
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Reviewed-on: https://chromium-review.googlesource.com/852952
Commit-Queue: Tibor Goldschwendt <[email protected]>
Reviewed-by: Tibor Goldschwendt <[email protected]>
Cr-Commit-Position: refs/heads/master@{#527426}
6 files changed