Refactoring benchmarks for perf bot efficiency.

tools/perf/perf_tools/first_paint_time_benchmark.py

-# Copyright (c) 2012 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.
-
-# The test takes a list of URLs through stdin and prints results in CSV format.
-# Example: python run_scroll_test.py < data/urls.txt > test_results.csv
-from telemetry import multi_page_benchmark
-from telemetry import util
-
-class FirstPaintTimeBenchmark(multi_page_benchmark.MultiPageBenchmark):
-  def MeasurePage(self, _, tab, results):
-    if tab.browser.is_content_shell:
-      results.Add('first_paint', 'seconds', 'unsupported')
-      return
-
-    tab.runtime.Execute("""
-        window.__rafFired = false;
-        window.webkitRequestAnimationFrame(function() {
-            window.__rafFired  = true;
-        });
-    """)
-    util.WaitFor(lambda: tab.runtime.Evaluate('window.__rafFired'), 60)
-
-    first_paint_secs = tab.runtime.Evaluate(
-      'window.chrome.loadTimes().firstPaintTime - ' +
-      'window.chrome.loadTimes().requestTime')
-
-    results.Add('first_paint', 'seconds', round(first_paint_secs, 1))