Attempt to fix chromium.gpu.fyi/Linux ChromiumOS Ozone Builder.

My change in #486768 looks to have broken the Linux Chromium Ozone
Builder which, confusingly, doesn't actually seem to be building
ChromiumOS, but rather, a variant of the desktop linux build
that uses Linux + Ozone + the system libdrm and libgbm libs.

TBR=jmadill@chromium.org, kbr@chromium.org
NOTRY=true
BUG=671355

Change-Id: I99d7501f9821eaae10affd999790b9bc87369f2a
Reviewed-on: https://chromium-review.googlesource.com/572301Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486894}

tools/mb/mb_config.pyl

@@ -259,7 +259,8 @@
       'GPU Win x64 Builder': 'gpu_tests_deqp_gles_release_trybot',
       'GPU Win x64 Builder (dbg)': 'gpu_tests_deqp_gles_debug_trybot',
       'Linux ChromiumOS Builder': 'gpu_fyi_tests_chromeos_release_trybot',
-      'Linux ChromiumOS Ozone Builder': 'gpu_fyi_tests_chromeos_release_trybot',
+      # This is, confusingly, apparently not actually building ChromiumOS.
+      'Linux ChromiumOS Ozone Builder': 'gpu_fyi_tests_ozone_linux_system_gbm_libdrm_release_trybot',
       'Linux GPU TSAN Release': 'gpu_fyi_tests_release_trybot_tsan',
       'Mac GPU ASAN Release': 'gpu_fyi_tests_release_trybot_asan',
     },
@@ -1234,6 +1235,10 @@
       'gpu_fyi_tests', 'debug_trybot',
     ],
 
+    'gpu_fyi_tests_ozone_linux_system_gbm_libdrm_release_trybot': [
+      'gpu_fyi_tests', 'ozone_linux', 'system_gbm_libdrm', 'release_trybot',
+    ],
+
     'gpu_fyi_tests_release_trybot': [
       'gpu_fyi_tests', 'release_trybot',
     ],