Refactor benchmark v8.runtime_stats.top_25 to be cleaner

1) Merge the abstract class _Top25RuntimeStats with V8Top25RuntimeStats since it's the only one inherit from the abstract class.
2) Remove the disabling Android in perf/expectations.config & switch to use SUPPORTED_PLATFORMS which is meant for permanent disabling logic like this case

Change-Id: I07fecfd3d9cce3e7d35ac71b274bb9416f0cdcac

TBR=perezju@chromium.org

Change-Id: I07fecfd3d9cce3e7d35ac71b274bb9416f0cdcac
Reviewed-on: https://chromium-review.googlesource.com/1175928Reviewed-by: Ned Nguyen <nednguyen@google.com>
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#583336}

tools/perf/benchmarks/v8.py

@@ -6,12 +6,26 @@ from core import perf_benchmark
 
 import page_sets
 
+from telemetry import story
 from telemetry import benchmark
 from telemetry.timeline import chrome_trace_category_filter
 from telemetry.web_perf import timeline_based_measurement
 
 
-class _Top25RuntimeStats(perf_benchmark.PerfBenchmark):
+@benchmark.Info(emails=['cbruni@chromium.org'])
+class V8Top25RuntimeStats(perf_benchmark.PerfBenchmark):
+  """Runtime Stats benchmark for a 25 top V8 web pages.
+
+  Designed to represent a mix between top websites and a set of pages that
+  have unique V8 characteristics.
+  """
+
+  SUPPORTED_PLATFORMS = [story.expectations.ALL_DESKTOP]
+
+  @classmethod
+  def Name(cls):
+    return 'v8.runtime_stats.top_25'
+
   def SetExtraBrowserOptions(self, options):
     options.AppendExtraBrowserArgs(
       '--enable-blink-features=BlinkRuntimeCallStats')
@@ -49,18 +63,5 @@ class _Top25RuntimeStats(perf_benchmark.PerfBenchmark):
     tbm_options.SetTimelineBasedMetrics(['runtimeStatsMetric'])
     return tbm_options
 
-
-@benchmark.Info(emails=['cbruni@chromium.org'])
-class V8Top25RuntimeStats(_Top25RuntimeStats):
-  """Runtime Stats benchmark for a 25 top V8 web pages.
-
-  Designed to represent a mix between top websites and a set of pages that
-  have unique V8 characteristics.
-  """
-
-  @classmethod
-  def Name(cls):
-    return 'v8.runtime_stats.top_25'
-
   def CreateStorySet(self, options):
     return page_sets.V8Top25StorySet()

tools/perf/expectations.config

@@ -287,7 +287,6 @@ crbug.com/799080 [ Nexus_5X Android_Webview ] v8.browsing_mobile-future/browse:s
 crbug.com/770982 [ Win ] v8.detached_context_age_in_gc/Docs_(1_open_document_tab) [ Skip ]
 crbug.com/812618 [ Android_Webview ] v8.detached_context_age_in_gc/Docs_(1_open_document_tab) [ Skip ]
 
-# Benchmark: v8.runtime_stats.top_25
 crbug.com/664318 [ Android ] v8.runtime_stats.top_25/* [ Skip ]
 
 # Benchmark: wasm