Add cron-linux-clang-rel-x64 for running cron jobs on CI

This bot will be used to regenerate the fuzzer seed corpus
periodically.

Bug: dawn:629
Change-Id: I9036690b85cfe602188aa891a32f03923b797463
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/38321
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>

infra/config/global/cr-buildbucket.cfg

@@ -112,6 +112,12 @@ builder_mixins {
     EOF
   }
 }
+builder_mixins {
+  name: "gen_fuzz_corpus"
+  recipe {
+    properties_j: "gen_fuzz_corpus:true"
+  }
+}
 
 buckets {
   name: "luci.dawn.ci"
@@ -219,6 +225,14 @@ buckets {
       mixins: "release"
       mixins: "x64"
     }
+
+    builders {
+      name: "cron-linux-clang-rel-x64"
+      mixins: "linux"
+      mixins: "release"
+      mixins: "x64"
+      mixins: "gen_fuzz_corpus"
+    }
   }
 }
 

infra/config/global/luci-milo.cfg

@@ -68,6 +68,12 @@ consoles {
     category: "win|msvc"
     short_name: "rel"
   }
+
+  builders {
+    name: "buildbucket/luci.dawn.ci/cron-linux-clang-rel-x64"
+    category: "cron|linux|clang|rel"
+    short_name: "x64"
+  }
 }
 
 consoles {

infra/config/global/luci-scheduler.cfg

@@ -148,3 +148,15 @@ job {
     builder: "win-msvc-rel-x64"
   }
 }
+
+job {
+  id: "cron-linux-clang-rel-x64"
+  realm: "ci"
+  schedule: "0 0 0 * * * *"
+  acl_sets: "default"
+  buildbucket {
+    server: "cr-buildbucket.appspot.com"
+    bucket: "luci.dawn.ci"
+    builder: "cron-linux-clang-rel-x64"
+  }
+}