[fuchsia] Generate BUILD.gn from SDK metadata, migrate FIDL targets.

This script uses the metadata JSON files in the SDK to generate a
BUILD.gn in //third_party/fuchsia-sdk/sdk. The build file is
regenerated whenever a new SDK is downloaded using "gclient sync".

Only FIDL libraries are migrated for now. Additional metadata types can
be migrated in followup CLs.


Bug: 888753
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: If87010006cd23e90d970da4cb84e6de35804b7dd
Reviewed-on: https://chromium-review.googlesource.com/1241842
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: Kevin Marshall <kmarshall@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#594360}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: dfd34b91e8de763ae7fc52eb12a7534a3e4b97a9
3 files changed