[odnoklassniki] add support for Schemeless embed extraction

youtube_dl/extractor/odnoklassniki.py

@@ -1,6 +1,8 @@
 # coding: utf-8
 from __future__ import unicode_literals
 
+import re
+
 from .common import InfoExtractor
 from ..compat import (
     compat_etree_fromstring,
@@ -121,6 +123,13 @@ class OdnoklassnikiIE(InfoExtractor):
         'only_matching': True,
     }]
 
+    @staticmethod
+    def _extract_url(webpage):
+        mobj = re.search(
+            r'<iframe[^>]+src=(["\'])(?P<url>(?:https?:)?//(?:odnoklassniki|ok)\.ru/videoembed/.+?)\1', webpage)
+        if mobj:
+            return mobj.group('url')
+
     def _real_extract(self, url):
         start_time = int_or_none(compat_parse_qs(
             compat_urllib_parse_urlparse(url).query).get('fromTime', [None])[0])