benchmarks: Add a warm story to startup.mobile

For the warm story we avoid flushing caches. Metrics will need more
polishing for properly omitting the first result. This should be done
for the cold benchmark as well, hence we'd still have a good separation
between the benchmark driver and the metrics.

Bug: 760498
Change-Id: Ie061852bd1c8893f5ea57b67c85a383bedf26a7c
Reviewed-on: https://chromium-review.googlesource.com/1203936Reviewed-by: Ned Nguyen <nednguyen@google.com>
Commit-Queue: Egor Pasko <pasko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#588829}

tools/perf/benchmarks/startup_mobile.py

@@ -62,11 +62,12 @@ class _MobileStartupSharedState(story_module.SharedState):
     self.platform.network_controller.Close()
     self.platform.SetFullPerformanceModeEnabled(False)
 
-  def LaunchBrowser(self, url):
-    self.platform.FlushDnsCache()
-    # TODO(crbug.com/811244): Determine whether this ensures the page cache is
-    # cleared after |FlushOsPageCaches()| returns.
-    self._possible_browser.FlushOsPageCaches()
+  def LaunchBrowser(self, url, flush_caches):
+    if flush_caches:
+      self.platform.FlushDnsCache()
+      # TODO(crbug.com/811244): Determine whether this ensures the page cache is
+      # cleared after |FlushOsPageCaches()| returns.
+      self._possible_browser.FlushOsPageCaches()
     self.platform.WaitForBatteryTemperature(35)
     self.platform.StartActivity(
         intent.Intent(package=self._possible_browser.settings.package,
@@ -119,21 +120,32 @@ class _MobileStartupSharedState(story_module.SharedState):
     return True
 
 
+def _DriveMobileStartupWithIntent(state, flush_caches):
+  for _ in xrange(10):
+    # TODO(pasko): Find a way to fail the benchmark when WPR is set up
+    # incorrectly and error pages get loaded.
+    state.LaunchBrowser('http://bbc.co.uk', flush_caches)
+    with state.FindBrowser() as browser:
+      action_runner = browser.foreground_tab.action_runner
+      action_runner.tab.WaitForDocumentReadyStateToBeComplete()
+
+
 class _MobileStartupWithIntentStory(story_module.Story):
   def __init__(self):
     super(_MobileStartupWithIntentStory, self).__init__(
         _MobileStartupSharedState, name='intent:coldish:bbc')
-    self._action_runner = None
 
   def Run(self, state):
-    """Drives the benchmark with repetitions."""
-    # TODO(pasko): Find a way to fail the benchmark when WPR is set up
-    # incorrectly and error pages get loaded.
-    for _ in xrange(10):
-      state.LaunchBrowser('http://bbc.co.uk')
-      with state.FindBrowser() as browser:
-        action_runner = browser.foreground_tab.action_runner
-        action_runner.tab.WaitForDocumentReadyStateToBeComplete()
+    _DriveMobileStartupWithIntent(state, flush_caches=True)
+
+
+class _MobileStartupWithIntentStoryWarm(story_module.Story):
+  def __init__(self):
+    super(_MobileStartupWithIntentStoryWarm, self).__init__(
+        _MobileStartupSharedState, name='intent:warm:bbc')
+
+  def Run(self, state):
+    _DriveMobileStartupWithIntent(state, flush_caches=False)
 
 
 class _MobileStartupStorySet(story_module.StorySet):
@@ -142,6 +154,7 @@ class _MobileStartupStorySet(story_module.StorySet):
           archive_data_file='../page_sets/data/startup_pages.json',
           cloud_storage_bucket=story_module.PARTNER_BUCKET)
     self.AddStory(_MobileStartupWithIntentStory())
+    self.AddStory(_MobileStartupWithIntentStoryWarm())
 
 
 # The mobile startup benchmark uses specifics of AndroidPlatform and hardcodes

tools/perf/page_sets/data/startup_pages.json

@@ -3,6 +3,9 @@
         "intent:coldish:bbc": {
             "DEFAULT": "startup_pages_000.wprgo"
         },
+        "intent:warm:bbc": {
+            "DEFAULT": "startup_pages_000.wprgo"
+        },
         "http://bbc.co.uk": {
             "DEFAULT": "startup_pages_000.wprgo"
         },