Ported media stream track enable-disable test to content module.

Also improves the tests to check that audio muting doesn't mute video
and vice versa.

BUG=328196,331045

Review URL: https://codereview.chromium.org/120773003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243591 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243591
skia: Use discardable memory for scaled image cache.

BUG=276675

Review URL: https://codereview.chromium.org/110863003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243592 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243592