ui: [Android] Hard code the GPU limit to 8MB for low-end devices

Landing with notry, the failure on win_rel cannot be related to this patch as this patch only affects Android.

NOTRY=true

BUG=

Review URL: https://chromiumcodereview.appspot.com/23931007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224523 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224523