Roll chromium_revision 6455c69..deaf2f7 (293954:295079)

Mainly to pick up recent yasm changes needed for
turning on libvpx in GN.

Summary of changes (git diff 6455c69..deaf2f7 DEPS):
* third_party/boringssl 7bdec13..a70c75c
* third_party/libjpeg_turbo 3963fbc..034e9a9
* third_party/libvpx d95585f..4947d55
* tools/gyp 1972:1977

I had to add src/third_party/junit/src to be ignored
due to http://crbug.com/417292.

BUG=3855, chromium:417292
TBR=pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/27539004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7313 4adac7df-926f-26a2-2b94-8c16560cd09d