Register metric Histogram names.

tracing/tracing/metrics/all_histogram_names.py

Index: tracing/tracing/metrics/all_histogram_names.py
diff --git a/tracing/tracing/metrics/all_histogram_names.py b/tracing/tracing/metrics/all_histogram_names.py
new file mode 100644
index 0000000000000000000000000000000000000000..a9847dc6f4bff0e2fefab39db8c6c197fd0d7fd1
--- /dev/null
+++ b/tracing/tracing/metrics/all_histogram_names.py
@@ -0,0 +1,33 @@
+# 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 json
+import os
+
+import tracing_project
+import vinn
+
+
+_ALL_HISTOGRAM_NAMES_CMD_LINE = os.path.join(
+    os.path.dirname(__file__), 'all_histogram_names_cmdline.html')
+
+
+def AllHistogramNames(metrics):
+  """ Returns a list of registered metrics.
+
+  Args:
+    metrics: a list of modules (string) to be loaded before discovering
+      the registered metrics.
+  """
+  assert isinstance(metrics, list)
+  project = tracing_project.TracingProject()
+  res = vinn.RunFile(
+      _ALL_HISTOGRAM_NAMES_CMD_LINE, source_paths=list(project.source_paths),
+      js_args=metrics)
+
+  if res.returncode != 0:
+    raise RuntimeError('Error running all_histogram_names_cmdline: ' +
+                       res.stdout)
+  else:
+    return [str(m) for m in json.loads(res.stdout)]