Add mac-cocoa-rel trybot config

Uses the same compile config as gpu_tests_release_trybot.

Bug: 855301
Change-Id: I70947b3bd21cbbe0519dcb37cb8c6bf844a3e274
Reviewed-on: https://chromium-review.googlesource.com/1179988Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Lindsay Pasricha <lindsayw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584199}

infra/config/global/cr-buildbucket.cfg

@@ -2662,6 +2662,7 @@ buckets {
     builders { mixins: "mac-try" name: "mac_chromium_variable_chrome" }
     builders { mixins: "mac-try" name: "mac_chromium_variable_deflake" }
     builders { mixins: "mac-try" name: "mac_chromium_variable_layout" }
+    builders { mixins: "mac-try" name: "mac-cocoa-rel" }
     builders { mixins: "mac-try" mixins: "nacl_sdk" name: "mac_nacl_sdk" }
     builders { mixins: "mac-try" mixins: "nacl_sdk_build" name: "mac_nacl_sdk_build" }
     builders {

infra/config/global/luci-milo.cfg

@@ -4172,6 +4172,9 @@ consoles {
   builders {
     name: "buildbot/tryserver.chromium.mac/mac_chromium_variable_layout"
   }
+  builders {
+    name: "buildbucket/luci.chromium.try/mac-cocoa-rel"
+  }
   builders {
     name: "buildbot/tryserver.chromium.mac/mac_nacl_sdk"
   }

tools/mb/mb_config.pyl

@@ -632,6 +632,7 @@
       'mac_chromium_compile_rel_ng': 'gpu_tests_release_trybot',
       'mac_chromium_dbg_ng': 'gpu_tests_debug_trybot',
       'mac_chromium_rel_ng': 'gpu_tests_release_trybot',
+      'mac-cocoa-rel': 'gpu_tests_release_trybot',
       'mac_nacl_sdk': 'release_bot',
       'mac_nacl_sdk_build': 'release_bot',
       'mac_optional_gpu_tests_rel': 'gpu_fyi_tests_release_trybot',