Updating Chromium to a new Fuchsia SDK

1. Check the Fuchsia-side job for a recent green archive. On the “SUCCEEDED” link, copy the SHA-1 from the gsutil.upload link of the upload fuchsia-sdk step.
2. Put that into Chromium's src.git DEPS in the fuchsia_sdk step.
3. gclient sync && ninja ... and make sure things go OK locally.
4. Upload the roll CL, making sure to include the fuchsia trybot. Tag the roll with Bug: 707030.

If you would like to build an SDK locally, tools/fuchsia/local-sdk.py tries to do this (so you can iterate on ToT Fuchsia against your Chromium build), however it's simply a copy of the steps run on the bot above, and so may be out of date.

In order to sync a Fuchsia tree to the state matching an SDK hash, you can use:

jiri update https://storage.googleapis.com/fuchsia/jiri/snapshots/SDK_HASH_HERE

If you are waiting for a Zircon CL to roll into the SDK, you can check the status of the Zircon roller. Checking the bot's list of CLs might be useful too.