Introduce OutputFormatter interface and wire it through PageTestResults.

tools/telemetry/telemetry/results/csv_page_measurement_results.py

Index: tools/telemetry/telemetry/results/csv_page_measurement_results.py
diff --git a/tools/telemetry/telemetry/results/csv_page_measurement_results.py b/tools/telemetry/telemetry/results/csv_page_measurement_results.py
deleted file mode 100644
index 8d396354423704e09df5d9fdbac4db241c5e6c66..0000000000000000000000000000000000000000
--- a/tools/telemetry/telemetry/results/csv_page_measurement_results.py
+++ /dev/null
@@ -1,71 +0,0 @@
-# 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 csv
-
-from telemetry.results import page_measurement_results
-from telemetry.value import merge_values
-
-
-class CsvPageMeasurementResults(
-    page_measurement_results.PageMeasurementResults):
-  def __init__(self, output_stream):
-    super(CsvPageMeasurementResults, self).__init__(output_stream)
-    self._results_writer = csv.writer(self._output_stream)
-    self._representative_value_names = None
-
-  def PrintSummary(self):
-    try:
-      values = merge_values.MergeLikeValuesFromSamePage(
-          self.all_page_specific_values)
-      self._OutputHeader(values)
-      value_groups_by_page = merge_values.GroupStably(
-          values, lambda value: value.page.url)
-      for values_for_page in value_groups_by_page:
-        self._OutputValuesForPage(values_for_page[0].page, values_for_page)
-    finally:
-      super(CsvPageMeasurementResults, self).PrintSummary()
-
-  def _OutputHeader(self, values):
-    """Output the header rows.
-
-    This will retrieve the header string from the given values. As a
-    results, you would typically pass it all of the recorded values at
-    the end of the entire telemetry run. In cases where each page
-    produces the same set of value names, you may call this method
-    with that set of values.
-
-    Args:
-      values: A set of values from which to extract the header string,
-          which is the value name and the units.
-    """
-    representative_values = {}
-    for value in values:
-      if value.name not in representative_values:
-        representative_values[value.name] = value
-    self._representative_value_names = list(
-        representative_values.keys())
-    self._representative_value_names.sort()
-
-    row = ['page_name']
-    for value_name in self._representative_value_names:
-      units = representative_values[value_name].units
-      row.append('%s (%s)' % (value_name, units))
-    self._results_writer.writerow(row)
-    self._output_stream.flush()
-
-  def _OutputValuesForPage(self, page, page_values):
-    row = [page.display_name]
-    values_by_value_name = {}
-    for value in page_values:
-      values_by_value_name[value.name] = value
-
-    for value_name in self._representative_value_names:
-      value = values_by_value_name.get(value_name, None)
-      if value and value.GetRepresentativeNumber():
-        row.append('%s' % value.GetRepresentativeNumber())
-      else:
-        row.append('-')
-    self._results_writer.writerow(row)
-    self._output_stream.flush()