Tab audio indicator: Use animation container on Mac

When showning an audio indicator on multiple tabs, the CPU usage on
my machine is:
  1 tab: 1.5%
  2 tab: 2.5%
  3 tab: 3.2%

This CL uses a common animation container for all tabs in a window.
This changes the CPU usage to:
  1 tab: 1.5%
  2 tab: 1.5%
  3 tab: 1.5%

BUG=3541

Review URL: https://chromiumcodereview.appspot.com/13867007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@195059 0039d316-1c4b-4281-b951-d872f2087c98
10 files changed