Add Metal compile bot to CQ

Bug: skia:
Change-Id: Ifaf94d100bf4213ee405086f72313884ef003486
Reviewed-on: https://skia-review.googlesource.com/60340
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Ravi Mistry <rmistry@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
diff --git a/infra/branch-config/cq.cfg b/infra/branch-config/cq.cfg
index f218054..9eb2001 100644
--- a/infra/branch-config/cq.cfg
+++ b/infra/branch-config/cq.cfg
@@ -39,6 +39,7 @@
       builders { name: "Build-Debian9-GCC-arm-Debug-Chromecast" }
       builders { name: "Build-Debian9-GCC-x86_64-Debug-NoGPU" }
       builders { name: "Build-Debian9-GCC-x86_64-Release" }
+      builders { name: "Build-Mac-Clang-x86_64-Debug-Metal" }
       builders { name: "Build-Mac-Clang-x86_64-Release" }
       builders { name: "Build-Win-Clang-x86_64-Release-Vulkan" }
       builders { name: "Build-Win-MSVC-x86-Debug" }