Remove GL context parameters from {E,VA}VDA.

gl{x}_context is not directly used in {E,VA}VDA anymore, so remove it. The
classes will call make_context_current_ callbacks when a valid context
is required and error out if it fails.

BUG=None
TEST=build, video playback

Review URL: https://codereview.chromium.org/109983003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241481 0039d316-1c4b-4281-b951-d872f2087c98
Prefix string16 in chrome/browser code to turn on PRESUBMIT.py that checks in
this directory.

R=sky@chromium.org
BUG=329295
TEST=git grep string16 chrome/browser | grep -v base::string16 | grep -v string16\.h

Review URL: https://codereview.chromium.org/103213010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241482 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241482
Suppress uninitialized read in media::ConvertYUVToRGB32_C

TBR=zhaoqin@chromium.org
BUG=113076

Review URL: https://codereview.chromium.org/110863007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241483 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241483