Generate proto traces on linux-perf-fyi bot

Turns on the --experimental-proto-trace-format flag to test proto trace
generation on bots. Uses the power.desktop benchmark to test metrics
computation.

TBR=crouleau@chromium.org

Bug: 990304
Change-Id: If9a2595a7e41a824d1f23638337806747782b319
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1939968
Commit-Queue: Mikhail Khokhlov <khokhlov@google.com>
Auto-Submit: Mikhail Khokhlov <khokhlov@google.com>
Reviewed-by: Juan Antonio Navarro Pérez <perezju@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720163}

testing/buildbot/chromium.perf.fyi.json

@@ -146,14 +146,15 @@
           "-v",
           "--browser=release",
           "--upload-results",
-          "--benchmarks=blink_perf.layout_ng,blink_perf.paint_layout_ng,loading.desktop_layout_ng",
-          "--output-format=histograms"
+          "--benchmarks=power.desktop",
+          "--output-format=histograms",
+          "--experimental-proto-trace-format"
         ],
         "isolate_name": "performance_test_suite",
         "merge": {
           "script": "//tools/perf/process_perf_results.py"
         },
-        "name": "blink_perf.layout_ng",
+        "name": "power.desktop",
         "override_compile_targets": [
           "performance_test_suite"
         ],

tools/perf/core/perf_data_generator.py

@@ -140,14 +140,11 @@ FYI_BUILDERS = {
       {
         'isolate': 'performance_test_suite',
         'extra_args': [
-            '--benchmarks=%s' % ','.join((
-                'blink_perf.layout_ng',
-                'blink_perf.paint_layout_ng',
-                'loading.desktop_layout_ng',
-            )),
+            '--benchmarks=%s' % 'power.desktop',
             '--output-format=histograms',
+            '--experimental-proto-trace-format',
         ],
-        'name': 'blink_perf.layout_ng',
+        'name': 'power.desktop',
       }
     ],
     'platform': 'linux',