Update docs on wrangling and standalone infra.

infra/ANGLEWrangling.md

+# ANGLE Wrangling
+
+As an ANGLE Sheriff. Your job is to:
+
+ 1. Keep the [ANGLE Try Waterfall](https://ci.chromium.org/p/chromium/g/angle.try/builders) in good working order.
+ 1. Monitor the [Chromium GPU FYI Waterfall](https://ci.chromium.org/p/chromium/g/chromium.gpu.fyi/console) and respond to ANGLE bugs.
+ 1. Control and monitor the [ANGLE auto-roller](https://autoroll.skia.org/r/angle-chromium-autoroll).
+ 1. Keep the [ANGLE Standalone Testers](README.md) in good working order.
+
+If you're not an ANGLE team member, you can contact us on the public ANGLE project [Google group](https://groups.google.com/forum/#!forum/angleproject).
+
+## Task 1: The Try Waterfall
+
+Your first job is to keep the
+[ANGLE Try Waterfall](https://ci.chromium.org/p/chromium/g/angle.try/builders) healthy.
+Some failures are expected on this waterfall. Developers might be testing
+expectedly buggy code. But persistent flakiness and failures should be
+reported and reverted.
+
+When encoutering an unexpected failure in your CLs please
+[file an ANGLE bug](http://anglebug.com/new) and cc the current ANGLE wrangler. If the
+failure is unrelated to ANGLE [file a Chromium bug](http://crbug.com/new) and
+mark the bug as `Hotlist-PixelWrangler`. Refer to
+[build.chromium.org](https://ci.chromium.org/p/chromium/g/main/console) to
+find the current ANGLE wrangler and GPU Pixel Wrangler.
+
+**NOTE: When all builds seem to be purple or otherwise broken:**
+
+This could be a major infrastructure outage. File a high-priority bug using [g.co/bugatrooper](http://g.co/bugatrooper).
+
+## Task 2: Respond to Bugs
+
+ANGLE bugs sometimes make it past the commit queue testing and into the master
+branch. This can be because of flaky tests or because the failures are
+specific to system configurations for which we lack full pre-commit testing
+support.
+
+The [Chromium GPU FYI Waterfall](https://ci.chromium.org/p/chromium/g/chromium.gpu.fyi/console)
+waterfall includes a number of these one-off specialized configurations.
+Monitor this console for persistent breakage that could be related to ANGLE.
+Also follow the `Internals>GPU>ANGLE` component on the Chromium issue tracker
+to be alerted to reports of breakage on the GPU.FYI waterfall. Googlers can use [sheriff-o-matic](https://sheriff-o-matic.appspot.com/chromium.gpu.fyi) to monitor the health of the GPU.FYI waterfall.
+
+Note that the GPU Pixel Wrangler is responsible for the *Chromium* bugs.
+Please file issues with the tag `Hotlist-PixelWrangler` for bugs that aren't
+caused by ANGLE regressions.
+
+*IMPORTANT*: Info to include in bug reports:
+
+ * Links to all first failing builds (eg first windows failure, first mac failure, etc).
+ * Related regression ranges. See below on how to determine the ANGLE regression range.
+ * Relevant error messages.
+ * Set components: `Internals>GPU` and/or `Internals>GPU>ANGLE`.
+ * cc relevant sheriffs or blame suspects.
+ * Set the `Hotlist-PixelWrangler` label.
+
+### How to determine the ANGLE regression range on the GPU.FYI bots:
+
+ 1. Open the first failing and last passing builds.
+ 1. For test failures: record `parent_got_angle_revision` in both builds.
+ 1. For compile failures record `got_angle_revision`.
+ 1. Use this URL: https://chromium.googlesource.com/angle/angle.git/+log/<last good revision>..<first bad revision>
+
+## Task 3: The Auto-Roller
+
+The [ANGLE auto-roller](https://autoroll.skia.org/r/angle-chromium-autoroll) automatically updates Chrome with the latest ANGLE changes.
+
+ 1. You will be cc'ed on ANGLE rolls. Please check failed rolls to verify there is no blocking breakage.
+ 1. You are also responsible for pausing the roller 24h before branch days, and resuming afterwards. See the [Chrome Release Schedule](https://chromiumdash.appspot.com/schedule).
+
+## Task 4: ANGLE Standalone Testing
+
+See more detailed instructions on by following [this link](README.md).

infra/README.md

+# ANGLE Standalone Testing Infrastructure
+
+In addition to the ANGLE try bots using Chrome, and the GPU.FYI bots, ANGLE
+has standalone testing on the Chrome infrastructure. Currently these tests are
+compile-only. This page is for maintaining the configurations that don't use
+Chromium. Also see the main instructions for [ANGLE Wrangling](ANGLEWrangling.md).
+
+It's the ANGLE team's responsibility for maintaining this testing
+infrastructure. The bot configurations live in four different repos and six
+branches.
+
+## Info Consoles
+
+Continuous builders for every ANGLE revision are found on the CI console:
+
+[https://ci.chromium.org/p/angle/g/ci/console](https://ci.chromium.org/p/angle/g/ci/console)
+
+Try jobs from pre-commit builds are found on the builders console:
+
+[https://ci.chromium.org/p/angle/g/try/builders](https://ci.chromium.org/p/angle/g/try/builders)
+
+## How to add a new build configuration
+
+ 1. [`bugs.chromium.org/p/chromium/issues/entry?template=Build+Infrastructure`](http://bugs.chromium.org/p/chromium/issues/entry?template=Build+Infrastructure):
+
+    * Request new slaves by filing an infra issue.
+
+ 1. [`chromium.googlesource.com/chromium/tools/build`](https://chromium.googlesource.com/chromium/tools/build):
+
+    * Update **`scripts/slave/recipes/angle.py`** with new the config.
+    * The recipe code requires 100% code coverage through mock bots, so add mock bot config to GenTests.
+    * Maybe run `./scripts/slave/recipes.py test train` to update checked-in golden files. This might no longer be necessary.
+
+ 1. [`chrome-internal.googlesource.com/infradata/config`](http://chrome-internal.googlesource.com/infradata/config):
+
+    * Update **`configs/chromium-swarm/bots.cfg`** to map from the slaves requested in step 1 to the builder configured in step 2.
+
+ 1. [`chromium.googlesource.com/angle/angle`](http://chromium.googlesource.com/angle/angle):
+
+    * Update **`infra/config/global/cr-buildbucket.cfg`** to add the new builder (to ci and try), and set the new config option.
+    * Update **`infra/config/global/luci-milo.cfg`** to make the builders show up on the ci and try waterfalls.
+    * Update **`infra/config/global/luci-scheduler.cfg`** to make the builders trigger on new commits or try jobs respectively.
+    * Update **`infra/config/cq.cfg`** to add the builder to the default CQ jobs (if desired).
+
+## Other Configuration
+
+There are other places where configuration for ANGLE infra lives. These are files that we shouldn't need to modify very often:
+
+ 1. [`chrome-internal.googlesource.com/infradata/config`](http://chrome-internal.googlesource.com/infradata/config):
+
+    * **`configs/luci-token-server/service_accounts.cfg`** (service account names)
+    * **`configs/chromium-swarm/pools.cfg`** (swarming pools)
+
+ 1. [`chromium.googlesource.com/chromium/tools/depot_tools`](http://chromium.googlesource.com/chromium/tools/depot_tools):
+
+    * **`recipes/recipe_modules/gclient/config.py`** (gclient config)