[system-health] Add support for disabling individual stories on individual platforms

tools/perf/benchmarks/system_health_smoke_test.py

Index: tools/perf/benchmarks/system_health_smoke_test.py
diff --git a/tools/perf/benchmarks/system_health_smoke_test.py b/tools/perf/benchmarks/system_health_smoke_test.py
index b4f2e91096005dedf3d27e1eb7ab4aba335d1063..0d3bf4df7954e1117c209025b015d094ae6d46f5 100644
--- a/tools/perf/benchmarks/system_health_smoke_test.py
+++ b/tools/perf/benchmarks/system_health_smoke_test.py
@@ -75,10 +75,14 @@ def _GenerateSmokeTestCase(benchmark_class, story_to_smoke_test):
     possible_browser = browser_finder.FindBrowser(options)
     if possible_browser is None:
       self.skipTest('Cannot find the browser to run the test.')
+
     if (SinglePageBenchmark.ShouldDisable(possible_browser) or
         not decorators.IsEnabled(benchmark_class, possible_browser)[0]):
       self.skipTest('Benchmark %s is disabled' % SinglePageBenchmark.Name())
 
+    if not story_to_smoke_test.CanRun(possible_browser):
+      self.skipTest('Story %s is disabled' % story_to_smoke_test.name)
+
     if self.id() in _DISABLED_TESTS:
       self.skipTest('Test is explictly disabled')