[system-health] Unify SH stories interface

tools/perf/benchmarks/system_health.py

Index: tools/perf/benchmarks/system_health.py
diff --git a/tools/perf/benchmarks/system_health.py b/tools/perf/benchmarks/system_health.py
index c53960f010249e13287aed2d2340b95335c0f401..b203d2a3d1fdf80860f3f7422923ca192d766bcc 100644
--- a/tools/perf/benchmarks/system_health.py
+++ b/tools/perf/benchmarks/system_health.py
@@ -78,9 +78,14 @@ class _MemorySystemHealthBenchmark(perf_benchmark.PerfBenchmark):
     options.SetTimelineBasedMetrics(['memoryMetric'])
     return options
 
+  def CreateStorySet(self, options):
+    return page_sets.SystemHealthStorySet(platform=self.PLATFORM,
+                                          story_name_regex=r'load:.*',
+                                          take_memory_measurement=True)
+
   @classmethod
   def Name(cls):
-    return 'system_health.memory_%s' % cls.page_set.PLATFORM
+    return 'system_health.memory_%s' % cls.PLATFORM
 
   @classmethod
   def ValueCanBeAddedPredicate(cls, value, is_first_result):
@@ -91,7 +96,7 @@ class _MemorySystemHealthBenchmark(perf_benchmark.PerfBenchmark):
 
 class DesktopMemorySystemHealth(_MemorySystemHealthBenchmark):
   """Desktop Chrome Memory System Health Benchmark."""
-  page_set = page_sets.DesktopSystemHealthStorySet
+  PLATFORM = 'desktop'
 
   @classmethod
   def ShouldDisable(cls, possible_browser):
@@ -102,7 +107,7 @@ class DesktopMemorySystemHealth(_MemorySystemHealthBenchmark):
 
 class MobileMemorySystemHealth(_MemorySystemHealthBenchmark):
   """Mobile Chrome Memory System Health Benchmark."""
-  page_set = page_sets.MobileSystemHealthStorySet
+  PLATFORM = 'mobile'
 
   @classmethod
   def ShouldDisable(cls, possible_browser):
@@ -111,6 +116,7 @@ class MobileMemorySystemHealth(_MemorySystemHealthBenchmark):
         possible_browser.browser_type == 'reference' and
         possible_browser.platform.GetDeviceTypeName() == 'Nexus 5X')
 
+
 @benchmark.Enabled('android-webview')
 class WebviewStartupSystemHealthBenchmark(perf_benchmark.PerfBenchmark):
   """Webview startup time benchmark