Update the active branches for the chromium project.

Bug: 1148845
Change-Id: I130de84b651b361cb7893c79b916123220a915be
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2537153Reviewed-by: Michael Moss <mmoss@chromium.org>
Commit-Queue: Garrett Beaty <gbeaty@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827348}

infra/config/generated/commit-queue.cfg

@@ -1625,6 +1625,7 @@ config_groups {
       ref_regexp: "refs/branch-heads/.*"
       ref_regexp_exclude: "refs/branch-heads/4240"
       ref_regexp_exclude: "refs/branch-heads/4280"
+      ref_regexp_exclude: "refs/branch-heads/4324"
     }
   }
   verifiers {

infra/config/generated/realms.cfg

@@ -141,6 +141,7 @@ realms {
     role: "role/swarming.poolUser"
     principals: "project:chromium-m86"
     principals: "project:chromium-m87"
+    principals: "project:chromium-m88"
     principals: "user:chromium-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
   }
 }
@@ -185,6 +186,7 @@ realms {
     principals: "group:chromium-led-users"
     principals: "project:chromium-m86"
     principals: "project:chromium-m87"
+    principals: "project:chromium-m88"
     principals: "user:infra-try-recipes-tester@chops-service-accounts.iam.gserviceaccount.com"
   }
 }

infra/config/project.star

@@ -107,17 +107,23 @@ def _milestone_details(*, project, ref, channel):
 # The milestone names and branch numbers of branches that we have builders
 # running for (including milestone-specific projects)
 # Branch numbers and milestones can be viewed in the chromium column at
-# https://chromiumdash.appspot.com/branches
-# The 2 highest milestones will be the ones with active branches
+# https://chromiumdash.appspot.com/releases
+# The 3rd portion of the version number is the branch number for the associated
+# milestone
 ACTIVE_MILESTONES = {
     "m86": _milestone_details(
         project = "chromium-m86",
         ref = "refs/branch-heads/4240",
-        channel = "Stable",
+        channel = "LTS-C",
     ),
     "m87": _milestone_details(
         project = "chromium-m87",
         ref = "refs/branch-heads/4280",
+        channel = "Stable",
+    ),
+    "m88": _milestone_details(
+        project = "chromium-m88",
+        ref = "refs/branch-heads/4324",
         channel = "Beta",
     ),
 }