[Fuchsia] Source Fuchsia boot images from separate GCS bucket.

Uses boot images supplied externally from the Fuchsia SDK.

Modifies the Cloud Storage download and decompression logic to skip
writing to disk, decompressing directly from the download stream
instead.

Bug: 977018
Change-Id: I06e378b4121853fe19dea4237cfb9eded23a1e0f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1668237
Commit-Queue: Kevin Marshall <kmarshall@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#671059}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 26478c00f7cb2bd744424736f0216286cda294f4
3 files changed