Use --extra_patchlevel for WebRTC patches on Chromium trybots.

The --extra_patchlevel flag was added in
https://codereview.chromium.org/1988583002/

In order to make it possible for WebRTC patches to apply in
src/third_party/webrtc of a Chromium checkout, one directory
level needs to be trimmed.

BUG=438952, 611808

Review-Url: https://codereview.chromium.org/1982243002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@300618 0039d316-1c4b-4281-b951-d872f2087c98

recipe_modules/bot_update/resources/bot_update.py

@@ -1126,6 +1126,10 @@ def apply_rietveld_issue(issue, patchset, root, server, _rev_map, _revision,
     for item in blacklist:
       cmd.extend(['--blacklist', item])
 
+  # TODO(kjellander): Remove this hack when http://crbug.com/611808 is fixed.
+  if root == 'src/third_party/webrtc':
+    cmd.extend(['--extra_patchlevel=1'])
+
   # Only try once, since subsequent failures hide the real failure.
   try:
     call(*cmd, tries=1)