Update buildbots to parse new telemetry JSON format.

scripts/slave/telemetry_utils.py

+#! /usr/bin/env python
+# Copyright (c) 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.
+
+"""Log parsing for telemetry tests."""
+
+import json
+import logging
+import os
+import tempfile
+
+
+class TelemetryResultsTracker(object):
+
+  def __init__(self):
+    self._chart_filename = None
+    self._ref_chart_filename = None
+
+  def GetArguments(self):
+    if not self._chart_filename:
+      (_, self._chart_filename) = tempfile.mkstemp()

[ghost stip (do not use), 2014/09/09 02:20:06]

you may need to close the file handle here, I'm not sure.

[sullivan, 2014/09/11 00:25:56]

Done.

+    if not self._ref_chart_filename:
+      (_, self._ref_chart_filename) = tempfile.mkstemp()
+    return (['--chart-output-filename', self._chart_filename,
+             '--ref-output-filename', self._ref_chart_filename])

[ghost stip (do not use), 2014/09/09 02:20:06]

I'm a bit confused about the ref output filename -- will the telemeterized
binary always write to it?

[sullivan, 2014/09/11 00:25:56]

No, only if there is a ref build in telemery._GenerateTelemetryCommandSequence.
Part of the reason I sent this for feedback before full review is that it's
pretty roundabout how the files get created and passed into telemetry. Not sure
if there's a better way to do it?

+
+  def _GetFileJson(self, filename):
+    try:
+      return json.loads(open(filename).read())
+    except (IOError, ValueError):
+      logging.error('Error reading telemetry results from %s', filename)
+      return None
+
+  def ChartJson(self):
+    return self._GetFileJson(self._chart_filename)
+
+  def RefJson(self):
+    return self._GetFileJson(self._ref_chart_filename)
+
+  def Cleanup(self):

[ghost stip (do not use), 2014/09/09 02:24:16]

I don't think cleanup is called by runtest.py in this patchset

[sullivan, 2014/09/11 00:25:56]

Done.

+    try:
+      os.remove(self._chart_filename)
+      os.remove(self._ref_chart_filename)

[ghost stip (do not use), 2014/09/09 02:20:06]

if the first one fails, we'll never get to the second one -- probably a good
idea to have a _try_to_delete() function with the try block that gets called
twice here

[sullivan, 2014/09/11 00:25:56]

Done.

+    except OSError:
+      pass
+
+  def IsChartJson(self):
+    """This is the new telemetry --chartjson output format."""
+    return True
+
+  def ProcessLine(self, line):
+    pass
+
+  def FailedTests(self):
+    return []
+
+  def SuppressionHashes(self):  # pylint: disable=R0201
+    return []
+
+  def ParsingErrors(self):  # pylint: disable=R0201
+    return []
+
+  def PerformanceSummary(self):
+    return 'TODO'