Use ImageLoader instead of ImageLoadingTracker (Part 12)

Update extensions::TabHelper class to use new ImageLoader class.

BUG=163929


Review URL: https://chromiumcodereview.appspot.com/11886073

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@178981 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed