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

tools/perf/page_sets/system_health/system_health_story.py

Index: tools/perf/page_sets/system_health/system_health_story.py
diff --git a/tools/perf/page_sets/system_health/system_health_story.py b/tools/perf/page_sets/system_health/system_health_story.py
index 394710d3c32945e299f8d5528c94f77fa04be051..78b9347b73e0787a72ea31f5d76a5c6da5243b1c 100644
--- a/tools/perf/page_sets/system_health/system_health_story.py
+++ b/tools/perf/page_sets/system_health/system_health_story.py
@@ -4,7 +4,9 @@
 
 from page_sets.system_health import platforms
 
+from telemetry import decorators
 from telemetry.page import page
+from telemetry.page import shared_page_state
 
 
 # Extra wait time after the page has loaded required by the loading metric. We
@@ -13,6 +15,32 @@ from telemetry.page import page
 _WAIT_TIME_AFTER_LOAD = 10
 
 
+class _SystemHealthSharedState(shared_page_state.SharedPageState):
+  """Shared state which enables disabling stories on individual platforms.
+
+  This class adds support for enabling/disabling individual stories on
+  individual platforms using the same approaches as for benchmarks:
+
+    1. Disabled/Enabled decorator:
+
+       @decorators.Disabled('win')
+       class Story(system_health_story.SystemHealthStory):
+         ...
+
+    2. ShouldDisable method:
+
+       class Story(system_health_story.SystemHealthStory):
+         ...
+
+         @classmethod
+         def ShouldDisable(cls, possible_browser):
+           return possible_browser.platform.GetOSName() == 'win'
+  """
+
+  def CanRunStory(self, story):
+    return story.CanRun(self.possible_browser)
+
+
 class _MetaSystemHealthStory(type):
   """Metaclass for SystemHealthStory."""
 
@@ -41,11 +69,28 @@ class SystemHealthStory(page.Page):
   def __init__(self, story_set, take_memory_measurement):
     case, group, _ = self.NAME.split(':')
     super(SystemHealthStory, self).__init__(
-        page_set=story_set, name=self.NAME, url=self.URL,
+        shared_page_state_class=_SystemHealthSharedState, page_set=story_set,
+        name=self.NAME, url=self.URL,
         credentials_path='../data/credentials.json',
         grouping_keys={'case': case, 'group': group})
     self._take_memory_measurement = take_memory_measurement
 
+  @classmethod
+  def CanRun(cls, possible_browser):
+    if (decorators.ShouldSkip(cls, possible_browser)[0] or
+        cls.ShouldDisable(possible_browser)):
+      return False
+    return True
+
+  @classmethod
+  def ShouldDisable(cls, possible_browser):
+    """Override this method to disable a story under specific conditions.
+
+    This method is modelled after telemetry.benchmark.Benchmark.ShouldDisable().
+    """
+    del possible_browser
+    return False
+
   def _Measure(self, action_runner):
     if self._take_memory_measurement:
       action_runner.MeasureMemory(deterministic_mode=True)