Roll chromium_revision ea769fd..6455c69 (re-land)

Mainly to pick up https://codereview.chromium.org/552013004

Summary of changes (git diff ea769fd..6455c69 DEPS):
* third_party/libvpx ceebbcc0..d95585f
* third_party/swarming e7d8b98..14b5fd82
* tools/gyp 1972:1973

TBR=pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/22349004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7139 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/DEPS b/DEPS
index d7be2c2..271a49f 100644
--- a/DEPS
+++ b/DEPS
@@ -12,7 +12,7 @@
   # Use this googlecode_url variable only if there is an internal mirror for it.
   # If you do not know, use the full path while defining your new deps entry.
   "googlecode_url": "http://%s.googlecode.com/svn",
-  "chromium_revision": "ea769fd2090e40950c84f9df851ffec5792bf04e",
+  "chromium_revision": "6455c698e51af65f57a8fe83547296218a5a7251",
 }
 
 # NOTE: Prefer revision numbers to tags for svn deps. Use http rather than