[toolchain-utils] Add tryjob flags to build Chrome from 9999 ebuild.

This CL updates the nightly tryjobs to build Chrome using the
9999 ebuild, to work with the CL that updates Chrome to not use
ThinLTO caching, so we can test LLD with our nightly builders.

BUG=None
TEST=Tested a tryjob with those flags and that CL, and it worked.

Change-Id: I3b1e77de6d1ead54f1696dc49987a37dd8db50ad
Reviewed-on: https://chromium-review.googlesource.com/1345889
Commit-Ready: Caroline Tice <cmtice@chromium.org>
Tested-by: Caroline Tice <cmtice@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
diff --git a/cros_utils/buildbot_utils.py b/cros_utils/buildbot_utils.py
index 911ea03..cde6583 100644
--- a/cros_utils/buildbot_utils.py
+++ b/cros_utils/buildbot_utils.py
@@ -87,13 +87,13 @@
 
   Args:
     chromeos_root: the path to the ChromeOS root, needed for finding chromite
-                   and launching the buildbot.
+      and launching the buildbot.
     buildbot_name: the name of the buildbot queue, such as lumpy-release or
-                   daisy-paladin.
+      daisy-paladin.
     patch_list: a python list of the patches, if any, for the buildbot to use.
     tryjob_flags: See cros tryjob --help for available options.
     build_toolchain: builds and uses the latest toolchain, rather than the
-                     prebuilt one in SDK.
+      prebuilt one in SDK.
 
   Returns:
     buildbucket id
@@ -110,8 +110,9 @@
 
   # Launch buildbot with appropriate flags.
   build = buildbot_name
-  command = ('cros tryjob --yes --json --nochromesdk  %s %s %s' %
-             (tryjob_flags, patch_arg, build))
+  command = (
+      'cros tryjob --pass-through=--chrome_rev=tot --yes --json --nochromesdk'
+      '  %s %s %s' % (tryjob_flags, patch_arg, build))
   print('CMD: %s' % command)
   _, out, _ = RunCommandInPath(chromeos_root, command)
   buildbucket_id = ParseTryjobBuildbucketId(out)
@@ -138,13 +139,13 @@
 
   Args:
     chromeos_root: the path to the ChromeOS root, needed for finding chromite
-                   and launching the buildbot.
+      and launching the buildbot.
     buildbot_name: the name of the buildbot queue, such as lumpy-release or
-                   daisy-paladin.
+      daisy-paladin.
     patch_list: a python list of the patches, if any, for the buildbot to use.
     tryjob_flags: See cros tryjob --help for available options.
     build_toolchain: builds and uses the latest toolchain, rather than the
-                     prebuilt one in SDK.
+      prebuilt one in SDK.
     async: don't wait for artifacts; just return the buildbucket id
 
   Returns: