[Telemetry] Remove old paint-rect speed index implementation.

tools/perf/metrics/speedindex.py

Index: tools/perf/metrics/speedindex.py
diff --git a/tools/perf/metrics/speedindex.py b/tools/perf/metrics/speedindex.py
index 389cd7e0c767565ab1fe4c272d7a6ce31b8e0724..4ada00809ee1b14a6f16270998d97434d4f2c82e 100644
--- a/tools/perf/metrics/speedindex.py
+++ b/tools/perf/metrics/speedindex.py
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import collections
+import logging
 
 from metrics import Metric
 from telemetry.image_processing import image_util
@@ -36,12 +37,15 @@ class SpeedIndexMetric(Metric):
     a PageTest, so that all the events can be captured. If it's called
     in DidNavigateToPage, that will be too late.
     """
-    self._impl = (VideoSpeedIndexImpl() if tab.video_capture_supported else
-                  PaintRectSpeedIndexImpl())
+    if not tab.video_capture_supported:
+      return
+    self._impl = VideoSpeedIndexImpl()
     self._impl.Start(tab)
 
   def Stop(self, _, tab):
-    """Stop timeline recording."""
+    """Stop recording."""
+    if not tab.video_capture_supported:
+      return
     assert self._impl, 'Must call Start() before Stop()'
     assert self.IsFinished(tab), 'Must wait for IsFinished() before Stop()'
     self._impl.Stop(tab)
@@ -50,9 +54,16 @@ class SpeedIndexMetric(Metric):
   # pylint: disable=W0221
   def AddResults(self, tab, results, chart_name=None):
     """Calculate the speed index and add it to the results."""
-    index = self._impl.CalculateSpeedIndex(tab)
-    # Release the tab so that it can be disconnected.
-    self._impl = None
+    try:
+      if tab.video_capture_supported:
+        index = self._impl.CalculateSpeedIndex(tab)
+        none_value_reason = None
+      else:
+        index = None
+        none_value_reason = 'Video capture is not supported.'
+    finally:
+      self._impl = None  # Release the tab so that it can be disconnected.
+
     results.AddValue(scalar.ScalarValue(
         results.current_page, '%s_speed_index' % chart_name, 'ms', index,
         description='Speed Index. This focuses on time when visible parts of '
@@ -70,15 +81,10 @@ class SpeedIndexMetric(Metric):
                     'there are two implementations: for Android and for '
                     'Desktop. The Android version uses video capture; the '
                     'Desktop one uses paint events and has extra overhead to '
-                    'catch paint events.'))
+                    'catch paint events.', none_value_reason=none_value_reason))
 
   def IsFinished(self, tab):
-    """Decide whether the timeline recording should be stopped.
-
-    When the timeline recording is stopped determines which paint events
-    are used in the speed index metric calculation. In general, the recording
-    should continue if there has just been some data received, because
-    this suggests that painting may continue.
+    """Decide whether the recording should be stopped.
 
     A page may repeatedly request resources in an infinite loop; a timeout
     should be placed in any measurement that uses this metric, e.g.:
@@ -182,145 +188,3 @@ class VideoSpeedIndexImpl(SpeedIndexImpl):
   def GetTimeCompletenessList(self, tab):
     assert self._time_completeness_list, 'Must call Stop() first.'
     return self._time_completeness_list
-
-
-class PaintRectSpeedIndexImpl(SpeedIndexImpl):
-
-  def __init__(self):
-    super(PaintRectSpeedIndexImpl, self).__init__()
-
-  def Start(self, tab):
-    tab.StartTimelineRecording()
-
-  def Stop(self, tab):
-    tab.StopTimelineRecording()
-
-  def GetTimeCompletenessList(self, tab):
-    events = tab.timeline_model.GetAllEvents()
-    viewport = self._GetViewportSize(tab)
-    paint_events = self._IncludedPaintEvents(events)
-    time_area_dict = self._TimeAreaDict(paint_events, viewport)
-    total_area = sum(time_area_dict.values())
-    assert total_area > 0.0, 'Total paint event area must be greater than 0.'
-    completeness = 0.0
-    time_completeness_list = []
-
-    # TODO(tonyg): This sets the start time to the start of the first paint
-    # event. That can't be correct. The start time should be navigationStart.
-    # Since the previous screen is not cleared at navigationStart, we should
-    # probably assume the completeness is 0 until the first paint and add the
-    # time of navigationStart as the start. We need to confirm what WPT does.
-    time_completeness_list.append(
-        (tab.timeline_model.GetAllEvents()[0].start, completeness))
-
-    for time, area in sorted(time_area_dict.items()):
-      completeness += float(area) / total_area
-      # Visual progress is rounded to the nearest percentage point as in WPT.
-      time_completeness_list.append((time, round(completeness, 2)))
-    return time_completeness_list
-
-  def _GetViewportSize(self, tab):
-    """Returns dimensions of the viewport."""
-    return tab.EvaluateJavaScript('[ window.innerWidth, window.innerHeight ]')
-
-  def _IncludedPaintEvents(self, events):
-    """Get all events that are counted in the calculation of the speed index.
-
-    There's one category of paint event that's filtered out: paint events
-    that occur before the first 'ResourceReceiveResponse' and 'Layout' events.
-
-    Previously in the WPT speed index, paint events that contain children paint
-    events were also filtered out.
-    """
-    def FirstLayoutTime(events):
-      """Get the start time of the first layout after a resource received."""
-      has_received_response = False
-      for event in events:
-        if event.name == 'ResourceReceiveResponse':
-          has_received_response = True
-        elif has_received_response and event.name == 'Layout':
-          return event.start
-      assert False, 'There were no layout events after resource receive events.'
-
-    first_layout_time = FirstLayoutTime(events)
-    paint_events = [e for e in events
-                    if e.start >= first_layout_time and e.name == 'Paint']
-    return paint_events
-
-  def _TimeAreaDict(self, paint_events, viewport):
-    """Make a dict from time to adjusted area value for events at that time.
-
-    The adjusted area value of each paint event is determined by how many paint
-    events cover the same rectangle, and whether it's a full-window paint event.
-    "Adjusted area" can also be thought of as "points" of visual completeness --
-    each rectangle has a certain number of points and these points are
-    distributed amongst the paint events that paint that rectangle.
-
-    Args:
-      paint_events: A list of paint events
-      viewport: A tuple (width, height) of the window.
-
-    Returns:
-      A dictionary of times of each paint event (in milliseconds) to the
-      adjusted area that the paint event is worth.
-    """
-    width, height = viewport
-    fullscreen_area = width * height
-
-    def ClippedArea(rectangle):
-      """Returns rectangle area clipped to viewport size."""
-      _, x0, y0, x1, y1 = rectangle
-      clipped_width = max(0, min(width, x1) - max(0, x0))
-      clipped_height = max(0, min(height, y1) - max(0, y0))
-      return clipped_width * clipped_height
-
-    grouped = self._GroupEventByRectangle(paint_events)
-    event_area_dict = collections.defaultdict(int)
-
-    for rectangle, events in grouped.items():
-      # The area points for each rectangle are divided up among the paint
-      # events in that rectangle.
-      area = ClippedArea(rectangle)
-      update_count = len(events)
-      adjusted_area = float(area) / update_count
-
-      # Paint events for the largest-area rectangle are counted as 50%.
-      if area == fullscreen_area:
-        adjusted_area /= 2
-
-      for event in events:
-        # The end time for an event is used for that event's time.
-        event_time = event.end
-        event_area_dict[event_time] += adjusted_area
-
-    return event_area_dict
-
-  def _GetRectangle(self, paint_event):
-    """Get the specific rectangle on the screen for a paint event.
-
-    Each paint event belongs to a frame (as in html <frame> or <iframe>).
-    This, together with location and dimensions, comprises a rectangle.
-    In the WPT source, this 'rectangle' is also called a 'region'.
-    """
-    def GetBox(quad):
-      """Gets top-left and bottom-right coordinates from paint event.
-
-      In the timeline data from devtools, paint rectangle dimensions are
-      represented x-y coordinates of four corners, clockwise from the top-left.
-      See: function WebInspector.TimelinePresentationModel.quadFromRectData
-      in file src/out/Debug/obj/gen/devtools/TimelinePanel.js.
-      """
-      x0, y0, _, _, x1, y1, _, _ = quad
-      return (x0, y0, x1, y1)
-
-    assert paint_event.name == 'Paint'
-    frame = paint_event.args['frameId']
-    return (frame,) + GetBox(paint_event.args['data']['clip'])
-
-  def _GroupEventByRectangle(self, paint_events):
-    """Group all paint events according to the rectangle that they update."""
-    result = collections.defaultdict(list)
-    for event in paint_events:
-      assert event.name == 'Paint'
-      result[self._GetRectangle(event)].append(event)
-    return result