Expose UseCounter::Feature enum out of blink as WebFeature

third_party/WebKit/public/platform/PRESUBMIT.py

+# 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.
+
+"""Blink frame presubmit script
+
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+for more details about the presubmit API built into gcl.
+"""
+
+
+def _RunUmaHistogramChecks(input_api, output_api):  # pylint: disable=C0103

[Rick Byers, 2017/05/23 19:51:49]

Looks like this just moves the existing rule without changing it at all except
the filename, right?  If you haven't alread, please test adding a new WebFeature
value to make double sure this is working before you land it.

[lunalu1, 2017/05/24 20:56:33]

I did test that. But thanks for the reminder

+    import sys
+
+    original_sys_path = sys.path
+    try:
+        sys.path = sys.path + [input_api.os_path.join(
+            input_api.PresubmitLocalPath(), '..', '..', '..', '..',
+            'tools', 'metrics', 'histograms')]
+        import update_histogram_enum  # pylint: disable=F0401
+    finally:
+        sys.path = original_sys_path
+
+    source_path = ''
+    for f in input_api.AffectedFiles():
+        if f.LocalPath().endswith('WebFeature.h'):
+            source_path = f.LocalPath()
+            break
+    else:
+        return []
+
+    start_marker = '^enum class WebFeature : uint32_t {'
+    end_marker = '^kNumberOfFeatures'
+    presubmit_error = update_histogram_enum.CheckPresubmitErrors(
+        histogram_enum_name='FeatureObserver',
+        update_script_name='update_use_counter_feature_enum.py',
+        source_enum_path=source_path,
+        start_marker=start_marker,
+        end_marker=end_marker,
+        strip_k_prefix=True)
+    if presubmit_error:
+        return [output_api.PresubmitPromptWarning(presubmit_error,
+                                                  items=[source_path])]
+    return []
+
+
+def CheckChangeOnUpload(input_api, output_api):  # pylint: disable=C0103
+    results = []
+    results.extend(_RunUmaHistogramChecks(input_api, output_api))
+    return results
+
+
+def CheckChangeOnCommit(input_api, output_api):  # pylint: disable=C0103
+    results = []
+    results.extend(_RunUmaHistogramChecks(input_api, output_api))
+    return results