roller: Add header_override property

Bug: b/370568381
Change-Id: If6a6b57c01639c787dfaf839aefcb7f5e4a4edb1
Reviewed-on: https://pigweed-review.googlesource.com/c/infra/recipes/+/239012
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed-service-accounts.iam.gserviceaccount.com>
Reviewed-by: Taylor Cramer <cramertj@google.com>
diff --git a/recipes/roller.proto b/recipes/roller.proto
index 91cbd38..c914520 100644
--- a/recipes/roller.proto
+++ b/recipes/roller.proto
@@ -82,4 +82,8 @@
   // via the subbuild module, which does not have a mechanism to modify an
   // existing roller's auto_roller_options (only can overwrite it).
   recipe_modules.fuchsia.auto_roller.Options override_auto_roller_options = 16;
+
+  // String to use after "roll: " in first line of commit message. Default is
+  // to auto-generate from all the rolls that modified the checkout.
+  string header_override = 17;
 }
diff --git a/recipes/roller.py b/recipes/roller.py
index b773bf7..77de495 100644
--- a/recipes/roller.py
+++ b/recipes/roller.py
@@ -125,6 +125,7 @@
         roll_prefix='roll:',
         send_comment=True,
         commit_divider=props.commit_divider,
+        header_override=props.header_override,
     )
 
     pres = api.step.empty('commit message').presentation