Roll chromium_revision 289723:291647

To pick up recent fixes after the Chromium Git switch.

Relevant changes pulled in by this roll:
* r291168 refactor sanitizer_options (we can now remove some hacks)
* r291647 roll of nss.gyp (its paths work with how we build for iOS).

BUG=2863,3731
R=iannucci@chromium.org, tommi@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/22489004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6967 4adac7df-926f-26a2-2b94-8c16560cd09d