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

tools/perf/page_sets/key_desktop_move_cases.py

 # Copyright 2015 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.page import page as page_module
 from telemetry.page import page_set as page_set_module
 
 
 class KeyDesktopMoveCasesPage(page_module.Page):
 
   def __init__(self, url, page_set, name='', credentials=None):
@@ skipping 66 matching lines @@
     scrollbar_mid_x_right_offset = scrollbar_width_ratio / 2
     scrollbar_mid_x = 1 - scrollbar_mid_x_right_offset
 
     # The End point of scrollbar (x remains same).
     scrollbar_end_mid_y = 1 - scrollbar_start_mid_y
     return scrollbar_mid_x, scrollbar_start_mid_y, scrollbar_end_mid_y
 
 
 class GoogleMapsPage(KeyDesktopMoveCasesPage):
 
-  """ Why: productivity, top google properties; Supports drag gesturee """
+  """ Why: productivity, top google properties; Supports drag gestures """
 
   def __init__(self, page_set):
     super(GoogleMapsPage, self).__init__(
         url='https://www.google.co.uk/maps/@51.5043968,-0.1526806',
         page_set=page_set,
         name='Maps')
 
   def RunNavigateSteps(self, action_runner):
     super(GoogleMapsPage, self).RunNavigateSteps(action_runner)
     action_runner.WaitForElement(selector='.widget-scene-canvas')
@@ skipping 14 matching lines @@
 
   """ Special cases for move gesture """
 
   def __init__(self):
     super(KeyDesktopMoveCasesPageSet, self).__init__(
       archive_data_file='data/key_desktop_move_cases.json',
       bucket=page_set_module.PARTNER_BUCKET)
 
     self.AddUserStory(GmailMouseScrollPage(self))
     self.AddUserStory(GoogleMapsPage(self))