Enable loading.desktop benchmark with network service enabled on perf fyi bot.

testing/buildbot/chromium.perf.fyi.extras.json

+{

[martiniss, 2017/07/06 01:30:46]

What is this file supposed to be doing? AFAIK, adding this file here won't do
anything at all.

[nednguyen, 2017/07/06 13:15:26]

This is used for generating the manual entries in
testing/buildbot/chromium.perf.fyi.json	(See change to
tools/perf/core/perf_data_generator.py)

[nednguyen, 2017/07/06 16:36:53]

I think we may want to move this file to tools/perf/contrib/ instead. The reason
is tools/perf/PRESUBMIT is only triggered if you touch any file under perf/
directory.

[yzshen1, 2017/07/06 17:43:29]

Done.

One thing is that I got the following Presubmit error:
"""You cannot add files to top level of contrib directory. Please moves these
files to a sub directory:

/usr/local/google/home/yzshen/src/cr1/src/tools/perf/contrib/chromium.perf.fyi.extras.json"""

I think it may be okay if adding such extras.json files is rare and reviewed by
the perf team. WDYT? Thanks!

+  "Mojo Linux Perf": {
+    "isolated_scripts": [
+      {
+        "args": [
+          "loading.desktop.network_service",
+          "-v",
+          "--upload-results",
+          "--output-format=chartjson",
+          "--browser=release"
+        ],
+        "isolate_name": "telemetry_perf_tests",
+        "name": "loading.desktop.network_service",
+        "override_compile_targets": [
+          "telemetry_perf_tests"
+        ],
+        "swarming": {
+          "can_use_on_swarming_builders": true,
+          "expiration": 36000,
+          "hard_timeout": 10800,
+          "ignore_task_failure": false,
+          "io_timeout": 3600
+        }
+      }
+    ]
+  }
+}