[Fuchsia] Enable viz_unittests on CQ bots.

viz_unittests has been running on the FYI bot without any issues, so it
should be safe to enabled it on CQ.

Bug: 961455
Change-Id: I86dc6e64421e84eb3263ba2432044a8c2ca26cb2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1737155
Auto-Submit: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#684492}

testing/buildbot/chromium.linux.json

@@ -2043,6 +2043,25 @@
         },
         "test": "ui_base_unittests"
       },
+      {
+        "args": [
+          "--child-arg=--ozone-platform=headless"
+        ],
+        "merge": {
+          "args": [],
+          "script": "//testing/merge_scripts/standard_gtest_merge.py"
+        },
+        "swarming": {
+          "can_use_on_swarming_builders": true,
+          "dimension_sets": [
+            {
+              "kvm": "1",
+              "os": "Ubuntu-16.04"
+            }
+          ]
+        },
+        "test": "viz_unittests"
+      },
       {
         "merge": {
           "args": [],

testing/buildbot/test_suite_exceptions.pyl

@@ -1625,8 +1625,6 @@
     'remove_from': [
       # chromium.win
       'Win10 Tests x64',
-      # chromium.linux
-      'Fuchsia x64',  # https://crbug.com/961455
     ],
   },
   'vr_android_unittests': {