Enable telemetry_perf_unittests on swarming.

testing/buildbot/chromium.fyi.json

Index: testing/buildbot/chromium.fyi.json
diff --git a/testing/buildbot/chromium.fyi.json b/testing/buildbot/chromium.fyi.json
index f9efec78265ce15b0c4ac76518d51a40ba8151b3..9672a1c609ac5648da898ffbbc330955a9fe4c8e 100644
--- a/testing/buildbot/chromium.fyi.json
+++ b/testing/buildbot/chromium.fyi.json
@@ -1417,6 +1417,9 @@
         }
       },
       {
+        "args": [
+          "--xvfb"

[Ken Russell (switch to Gerrit), 2016/06/01 01:18:10]

This looks wrong. This is a Mac bot and xvfb should not be necessary.

I see that you're folding the "--xvfb" flag into all the bot configurations
which run this test except for Android, but this would be a good opportunity to
fix some of the bots' setups and minimize the diffs in this CL. It should only
be needed on the Linux bots.

[ghost stip (do not use), 2016/06/01 08:42:25]

because --xvfb no longer on by default in gn_isolate_map.pyl

+        ],
         "isolate_name": "telemetry_perf_unittests",
         "name": "telemetry_perf_unittests",
         "override_compile_targets": [
@@ -2916,6 +2919,9 @@
         }
       },
       {
+        "args": [
+          "--xvfb"
+        ],
         "isolate_name": "telemetry_perf_unittests",
         "name": "telemetry_perf_unittests",
         "override_compile_targets": [
@@ -8720,6 +8726,9 @@
         }
       },
       {
+        "args": [
+          "--xvfb"
+        ],
         "isolate_name": "telemetry_perf_unittests",
         "name": "telemetry_perf_unittests",
         "override_compile_targets": [
@@ -8918,6 +8927,9 @@
         }
       },
       {
+        "args": [
+          "--xvfb"
+        ],
         "isolate_name": "telemetry_perf_unittests",
         "name": "telemetry_perf_unittests",
         "override_compile_targets": [
@@ -9251,6 +9263,9 @@
         }
       },
       {
+        "args": [
+          "--xvfb"
+        ],
         "isolate_name": "telemetry_perf_unittests",
         "name": "telemetry_perf_unittests",
         "override_compile_targets": [
@@ -9443,6 +9458,9 @@
         }
       },
       {
+        "args": [
+          "--xvfb"
+        ],
         "isolate_name": "telemetry_perf_unittests",
         "name": "telemetry_perf_unittests",
         "override_compile_targets": [