Disable service_worker.service_worker perf test.

This is using the deprecated Speed Index. Apparently something changed that
broke us. We aren't really using this benchmark and can probably delete it
outright but let's wait until the new PWA benchmark is landed.

Bug: 763153
Change-Id: I0fe734a145e9cf20b741f128e67456aff29e956c
Reviewed-on: https://chromium-review.googlesource.com/663799Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501555}

tools/perf/benchmarks/service_worker.py

@@ -178,9 +178,8 @@ class ServiceWorkerPerfTest(perf_benchmark.PerfBenchmark):
   def GetExpectations(self):
     class StoryExpectations(story.expectations.StoryExpectations):
       def SetExpectations(self):
-        self.DisableStory('first_load',
-                          [story.expectations.ALL_ANDROID],
-                          'crbug.com/736518, crbug.com/763153')
+        self.DisableBenchmark([story.expectations.ALL],
+                              'crbug.com/736518, crbug.com/763153')
     return StoryExpectations()