[Telemetry] Add benchmark that doesn't launch chrome and collects platform data.

tools/perf/page_sets/idle_platform.py

+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+import time
+
+from telemetry.page import page
+from telemetry.page import shared_page_state
+from telemetry import story
+
+
+class _IdleSharedState(shared_page_state.SharedPageState):
+  def __init__(self, test, finder_options, story_set, idle_time=30):
+    super(_IdleSharedState, self).__init__(test, finder_options, story_set)
+    self._idle_time = idle_time
+
+  def WillRunStory(self, _):
+    if not self.platform.tracing_controller.is_tracing_running:
+      # For TimelineBasedMeasurement benchmarks, tracing has already started.
+      # For PageTest benchmarks, tracing has not yet started. We need to make
+      # sure no tracing state is left before starting the browser for PageTest
+      # benchmarks.
+      self.platform.tracing_controller.ClearStateIfNeeded()
+
+  def RunStory(self, _):
+    time.sleep(self._idle_time)
+
+  def DidRunStory(self, results):
+    pass
+
+class IdlePlatformPage(page.Page):

[nednguyen, 2017/03/13 16:33:35]

Let inherit this from story, so that you don't need to force in the "url"
concept

[rnephew (Reviews Here), 2017/03/13 21:29:18]

Done, but now requires https://codereview.chromium.org/2749533003/ to land.

+  def __init__(self, url, page_set):
+    super(IdlePlatformPage, self).__init__(
+        url=url, page_set=page_set, credentials_path='data/credentials.json',
+        shared_page_state_class=_IdleSharedState, name='Idle Platform')
+
+
+class IdlePlatformPageSet(story.StorySet):
+  def __init__(self):
+    super(IdlePlatformPageSet, self).__init__(
+        archive_data_file=None,
+        cloud_storage_bucket=story.PARTNER_BUCKET)
+    # Page requires URL to be a valid.
+    self.AddStory(IdlePlatformPage('http://Idle Platform', self))