cc: Move manhattanDistance from tile priority to rect.

This patch moves TilePriority::manhattanDistance to
gfx::Rect::ManhattanInternalDistance. Associated unit tests
are moved as well.

R=enne, danakj

Review URL: https://codereview.chromium.org/108693002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239358 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239358
Measure time spent alt-tab cycling.

BUG=325229
TEST=Alt+tab, then find time recorded in chrome://histograms.

Review URL: https://codereview.chromium.org/108883002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239359 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239359