[Telemetry] Make tab video capture robust to multiple frames containing flash.

Previously, we assumed the initial tab contents flash could only appear in the
first frame. This makes us robust to it appearing in N initial frames.

BUG=323813
R=slamm@chromium.org, szym@chromium.org

Review URL: https://codereview.chromium.org/134843004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244969 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244969
Disabling NegotiateUnsupportedVideoCodec and NegotiateNonCryptoCall on Ozone

The 2 Webrtc tests are consistently timing out on the Ozone builder.

NOTRY=true

BUG=315392
R=dalecurtis@chromium.org

Review URL: https://codereview.chromium.org/139463003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244970 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244970