Add a note on android_optional_gpu_tests_rel trybot to manual rolls doc.

docs/rolling-deps.md

Index: docs/rolling-deps.md
diff --git a/docs/rolling-deps.md b/docs/rolling-deps.md
index e4cdfe52ea36b4abd32a7b0a774310fc8c57bf6f..93d833c76008f3a278a8a3bcd7af9470096504c4 100644
--- a/docs/rolling-deps.md
+++ b/docs/rolling-deps.md
@@ -40,3 +40,8 @@ a line like:
 Update the number to the git hash you want to roll to, and [contribute a
 codereview to chrome](http://www.chromium.org/developers/contributing-code)
 for your edit. If you are a Chromium committer, feel free to TBR this.
+
+Please also test the change on android\_optional\_gpu\_tests\_rel trybot.
+This can be accomplished by adding
+CQ\_INCLUDE\_TRYBOTS=master.tryserver.chromium.android:android\_optional\_gpu\_tests\_rel
+to the commit message.