Bug 1578661 - Add a crappy histogram parser for the devtools database, for probe-scraper. r=chutten

(And test it.)

Differential Revision: https://phabricator.services.mozilla.com/D46111

--HG--
extra : moz-landing-system : lando

toolkit/components/telemetry/build_scripts/mozparsers/parse_histograms.py

@@ -773,11 +773,35 @@ def from_counted_unknown_properties(filename, strict_type_checks):
     return histograms
 
 
+# This is only used for probe-scraper.
+def from_properties_db(filename, strict_type_checks):
+    histograms = collections.OrderedDict()
+    with open(filename, 'r') as f:
+        in_css_properties = False
+
+        for line in f:
+            if not in_css_properties:
+                if line.startswith("exports.CSS_PROPERTIES = {"):
+                    in_css_properties = True
+                continue
+
+            if line.startswith("};"):
+                break
+
+            if not line.startswith("  \""):
+                continue
+
+            name = line.split("\"")[1]
+            add_css_property_counters(histograms, name)
+    return histograms
+
+
 FILENAME_PARSERS = [
     (lambda x: from_json if x.endswith('.json') else None),
     (lambda x: from_nsDeprecatedOperationList if x == 'nsDeprecatedOperationList.h' else None),
     (lambda x: from_ServoCSSPropList if x == 'ServoCSSPropList.py' else None),
     (lambda x: from_counted_unknown_properties if x == 'counted_unknown_properties.py' else None),
+    (lambda x: from_properties_db if x == 'properties-db.js' else None),
 ]
 
 # Similarly to the dance above with buildconfig, usecounters may not be

toolkit/components/telemetry/tests/python/test_histogramtools_non_strict.py

@@ -65,6 +65,32 @@ class TestParser(unittest.TestCase):
         self.assertEqual(hist.n_buckets(), 101)
         self.assertEqual(hist.high(), 12)
 
+    def test_devtools_database_parsing(self):
+        db = path.join(TELEMETRY_ROOT_PATH,
+                       path.pardir,
+                       path.pardir,
+                       path.pardir,
+                       "devtools",
+                       "shared",
+                       "css",
+                       "generated",
+                       "properties-db.js")
+
+        histograms = list(parse_histograms.from_files([db], strict_type_checks=False))
+        histograms = [h.name() for h in histograms]
+
+        # Test a shorthand (animation)
+        self.assertTrue("USE_COUNTER2_CSS_PROPERTY_Animation_DOCUMENT" in histograms)
+
+        # Test a shorthand alias (-moz-animation).
+        self.assertTrue("USE_COUNTER2_CSS_PROPERTY_MozAnimation_DOCUMENT" in histograms)
+
+        # Test a longhand (animation-name)
+        self.assertTrue("USE_COUNTER2_CSS_PROPERTY_AnimationName_DOCUMENT" in histograms)
+
+        # Test a longhand alias (-moz-animation-name)
+        self.assertTrue("USE_COUNTER2_CSS_PROPERTY_MozAnimationName_DOCUMENT" in histograms)
+
     def test_current_histogram(self):
         HISTOGRAMS_PATH = path.join(TELEMETRY_ROOT_PATH, "Histograms.json")
         all_histograms = list(parse_histograms.from_files([HISTOGRAMS_PATH],