[system-health] Add support for recording stories directly through story set

Until now, System Health stories had to be recorded through a benchmark,
e.g. system_health.memory_*:

  tools/perf/record_wpr mobile_memory_system_health
  tools/perf/record_wpr desktop_memory_system_health

This goes against the idea of SH stories being reusable across multiple
benchmarks. Instead, it is now possible (and recommended) to record
directly through the story set:

  tools/perf/record_wpr mobile_system_health_story_set
  tools/perf/record_wpr desktop_system_health_story_set

This will ensure that all SH stories are recorded under the same
conditions (10s wait at the end of the story without a memory dump).

BUG=589726

Review-Url: https://codereview.chromium.org/2276943002
Cr-Commit-Position: refs/heads/master@{#414373}

tools/perf/page_sets/system_health/system_health_stories.py

@@ -31,6 +31,32 @@ class SystemHealthStorySet(story.StorySet):
       self.AddStory(story_class(self, take_memory_measurement))
 
 
+class DesktopSystemHealthStorySet(SystemHealthStorySet):
+  """Desktop user stories for the System Health Plan.
+
+  Note: This story set is only intended to be used for recording stories via
+  tools/perf/record_wpr. If you would like to use it in a benchmark, please use
+  the generic SystemHealthStorySet class instead (you'll need to override the
+  CreateStorySet method of your benchmark).
+  """
+  def __init__(self):
+    super(DesktopSystemHealthStorySet, self).__init__(
+        'desktop', take_memory_measurement=False)
+
+
+class MobileSystemHealthStorySet(SystemHealthStorySet):
+  """Mobile user stories for the System Health Plan.
+
+  Note: This story set is only intended to be used for recording stories via
+  tools/perf/record_wpr. If you would like to use it in a benchmark, please use
+  the generic SystemHealthStorySet class instead (you'll need to override the
+  CreateStorySet method of your benchmark).
+  """
+  def __init__(self):
+    super(MobileSystemHealthStorySet, self).__init__(
+        'mobile', take_memory_measurement=False)
+
+
 def _IterAllSystemHealthStoryClasses():
   start_dir = os.path.dirname(os.path.abspath(__file__))
   # Sort the classes by their names so that their order is stable and

tools/perf/page_sets/system_health/system_health_story.py

@@ -47,25 +47,11 @@ class SystemHealthStory(page.Page):
     self._take_memory_measurement = take_memory_measurement
 
   def _Measure(self, action_runner):
-    if self._ShouldMeasureMemory(action_runner):
+    if self._take_memory_measurement:
       action_runner.MeasureMemory(deterministic_mode=True)
     else:
       action_runner.Wait(_WAIT_TIME_AFTER_LOAD)
 
-  def _ShouldMeasureMemory(self, action_runner):
-    if not self._take_memory_measurement:
-      return False
-    # The check below is also performed in action_runner.MeasureMemory().
-    # However, we need to duplicate it here so that the story would wait for
-    # |_WAIT_TIME_AFTER_LOAD| seconds after load when recorded via the
-    # system_health.memory_* benchmarks.
-    # TODO(petrcermak): Make it possible (and mandatory) to record the story
-    # directly through the story set and remove this check.
-    tracing_controller = action_runner.tab.browser.platform.tracing_controller
-    if not tracing_controller.is_tracing_running:
-      return False  # Tracing is not running, e.g. when recording a WPR archive.
-    return True
-
   def _Login(self, action_runner):
     pass