Add smoothness test for hover during trackpad scrolling [perf implications]

tools/perf/page_sets/tough_scrolling_cases.py

Index: tools/perf/page_sets/tough_scrolling_cases.py
diff --git a/tools/perf/page_sets/tough_scrolling_cases.py b/tools/perf/page_sets/tough_scrolling_cases.py
index e76b519d59aa4ddcefa2e14f7f8f5cb120978692..5076a858e96ab7b4a816f3680cf7ad463ebc376f 100644
--- a/tools/perf/page_sets/tough_scrolling_cases.py
+++ b/tools/perf/page_sets/tough_scrolling_cases.py
@@ -1,24 +1,28 @@
 # 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.
+from telemetry.internal.actions import page_action
 from telemetry.page import page as page_module
 from telemetry.page import page_set as page_set_module
 
 
 class ToughFastScrollingCasesPage(page_module.Page):
 
-  def __init__(self, url, name, speed_in_pixels_per_second, page_set):
+  def __init__(self, url, name, speed_in_pixels_per_second, page_set,
+               synthetic_gesture_source):
     super(ToughFastScrollingCasesPage, self).__init__(
       url=url,
       page_set=page_set,
       name=name)
     self.speed_in_pixels_per_second = speed_in_pixels_per_second
+    self.synthetic_gesture_source = synthetic_gesture_source
 
   def RunPageInteractions(self, action_runner):
     with action_runner.CreateGestureInteraction('ScrollAction'):
       action_runner.ScrollPage(
           direction='down',
-          speed_in_pixels_per_second=self.speed_in_pixels_per_second)
+          speed_in_pixels_per_second=self.speed_in_pixels_per_second,
+          synthetic_gesture_source=self.synthetic_gesture_source)
 
 class ToughScrollingCasesPageSet(page_set_module.PageSet):
 
@@ -31,6 +35,7 @@ class ToughScrollingCasesPageSet(page_set_module.PageSet):
 
     fast_scrolling_page_name_list = [
       'text',
+      'text_hover',
       'canvas'
     ]
 
@@ -40,8 +45,12 @@ class ToughScrollingCasesPageSet(page_set_module.PageSet):
 
     for name in fast_scrolling_page_name_list:
       for speed in fast_scrolling_speed_list:
+        synthetic_gesture_source = page_action.GESTURE_SOURCE_DEFAULT
+        if "hover" in name:
+          synthetic_gesture_source = page_action.GESTURE_SOURCE_MOUSE
         self.AddUserStory(ToughFastScrollingCasesPage(
           'file://tough_scrolling_cases/' + name + '.html',
           name + '_' + str(speed).zfill(5) + '_pixels_per_second',
           speed,
-          self))
+          self,
+          synthetic_gesture_source))