Add os mixins to angle builders.

cr-buildbucket.cfg

@@ -18,7 +18,7 @@ acl_sets {
   }
   acls {
     role: SCHEDULER
-    identity: "angle-ci-builder@chops-service-accounts.appspot.com"
+    identity: "angle-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
   }
 }
 
@@ -38,6 +38,16 @@ acl_sets {
   }
 }
 
+builder_mixins {
+  name: "linux"
+  dimensions: "os:Ubuntu-14.04"
+}
+
+builder_mixins {
+  name: "win"
+  dimensions: "os:Windows"
+}
+
 buckets {
   name: "luci.angle.ci"
   acl_sets: "ci"
@@ -51,14 +61,16 @@ buckets {
         cipd_version: "refs/heads/master"
         name: "angle"
       }
-      service_account: "angle-ci-builder@chops-service-accounts.appspot.com"
+      service_account: "angle-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
     }
 
     builders {
       name: "linux"
+      mixins: "linux"
     }
     builders {
       name: "win-msvc"
+      mixins: "win"
     }
   }
 }
@@ -79,14 +91,16 @@ buckets {
         name: "angle"
         properties_j: "$depot_tools/bot_update:{\"apply_patch_on_gclient\":true}"
       }
-      service_account: "angle-try-builder@chops-service-accounts.appspot.com"
+      service_account: "angle-try-builder@chops-service-accounts.iam.gserviceaccount.com"
     }
 
     builders {
       name: "linux"
+      mixins: "linux"
     }
     builders {
       name: "win-msvc"
+      mixins: "win"
     }
   }
 }