Roll chromium deps to match webrtc. chromium builds in older deps didnt support…

Roll chromium deps to match webrtc.  chromium builds in older deps didnt support xcode 6.  This roll updates to a newer version to address the issue.
BUG=370
TESTED=try bots
R=tpsiaki@google.com

Review URL: https://webrtc-codereview.appspot.com/36709004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1223 16f28f9a-4ce2-e073-06de-1de4eb20be90

DEPS

@@ -8,7 +8,7 @@ vars = {
 
   # Roll the Chromium Git hash to pick up newer versions of all the
   # dependencies and tools linked to in setup_links.py.
-  "chromium_revision": "d8c90415d681a7c3727e3ef70873bc4f44dd3ab0",
+  'chromium_revision': '271c6cca48a6cef32c0f3add3b17b700707deec5',
 }
 
 hooks = [