Replace tab audio indicator graphic with approved asset from UX team.

Testing: Manually confirmed by running browser with --enable-audible-notifications flag and playing audio from the browser.

BUG=290550,178934
NOTRY=true
R=oshima@chromium.org

Review URL: https://codereview.chromium.org/26697003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227849 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227849