fix telemetry_perf_unittests on linux-trusty-rel

Need to use same arguments with 'Linux Tests'.

This is passed on
https://ci.chromium.org/p/chromium/builders/try/linux-trusty-rel/1

Bug: 974597
Change-Id: I3da2717787b0d1636e796e2c43aa5b265873ef82
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1660295
Commit-Queue: John Budorick <jbudorick@chromium.org>
Auto-Submit: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#669680}
diff --git a/testing/buildbot/chromium.linux.json b/testing/buildbot/chromium.linux.json
index 5ebb6876b..697ae96 100644
--- a/testing/buildbot/chromium.linux.json
+++ b/testing/buildbot/chromium.linux.json
@@ -10392,6 +10392,10 @@
         }
       },
       {
+        "args": [
+          "--xvfb",
+          "--jobs=1"
+        ],
         "isolate_name": "telemetry_perf_unittests",
         "merge": {
           "args": [],
diff --git a/testing/buildbot/test_suite_exceptions.pyl b/testing/buildbot/test_suite_exceptions.pyl
index e546dbb..cb20c9d 100644
--- a/testing/buildbot/test_suite_exceptions.pyl
+++ b/testing/buildbot/test_suite_exceptions.pyl
@@ -1374,6 +1374,12 @@
           '--jobs=1',
         ],
       },
+      'linux-trusty-rel': {
+        'args': [
+          '--xvfb',
+          '--jobs=1',
+        ],
+      },
       # chromium.mac
       # Disable parallelism on all Mac bots.
       'Mac10.10 Tests': {