[telemetry] Add support for BenchmarkResults that vary from page to page

tools/telemetry/telemetry/page_benchmark_value.py

Index: tools/telemetry/telemetry/page_benchmark_value.py
diff --git a/tools/telemetry/telemetry/page_benchmark_value.py b/tools/telemetry/telemetry/page_benchmark_value.py
new file mode 100644
index 0000000000000000000000000000000000000000..0a7c3a9b7100c9d445d03c449f03b0438c021c49
--- /dev/null
+++ b/tools/telemetry/telemetry/page_benchmark_value.py
@@ -0,0 +1,32 @@
+# Copyright (c) 2012 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.perf_tests_helper import GeomMeanAndStdDevFromHistogram
+
+def _Mean(l):
+  return float(sum(l)) / len(l) if len(l) > 0 else 0.0
+
+class PageBenchmarkValue(object):
+  def __init__(self, trace_name, units, value, chart_name, data_type):
+    self.trace_name = trace_name
+    self.units = units
+    self.value = value
+    self.chart_name = chart_name
+    self.data_type = data_type
+
+  @property
+  def measurement_name(self):
+    if self.chart_name:
+      return '%s.%s' % (self.chart_name, self.trace_name)
+    else:
+      return self.trace_name
+
+  @property
+  def output_value(self):
+    if self.data_type == 'histogram':
+      return GeomMeanAndStdDevFromHistogram(self.value)
+    elif isinstance(self.value, list):
+      return _Mean(self.value)
+    else:
+      return self.value
+