Add CsvOutputFormatter to Telemetry.

tracing/tracing/value/histograms_to_csv.py

Index: tracing/tracing/value/histograms_to_csv.py
diff --git a/tracing/tracing/value/histograms_to_csv.py b/tracing/tracing/value/histograms_to_csv.py
new file mode 100644
index 0000000000000000000000000000000000000000..ce1b90f55b10ba5f53837ddd19ac98f93834e9be
--- /dev/null
+++ b/tracing/tracing/value/histograms_to_csv.py
@@ -0,0 +1,22 @@
+# Copyright 2017 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 os
+import vinn
+import tracing_project
+
+def HistogramsToCsv(json_path):
+  """Convert HistogramSet JSON to CSV.
+
+  Args:
+    json_path: path to a file containing HistogramSet JSON
+
+  Returns:
+    a Vinn result object whose 'returncode' indicates whether there was an
+    exception, and whose 'stdout' contains CSV.
+  """
+  return vinn.RunFile(
+      os.path.join(os.path.dirname(__file__), 'histograms_to_csv_cmdline.html'),
+      source_paths=list(tracing_project.TracingProject().source_paths),
+      js_args=[os.path.abspath(json_path)])