Pass ui::LatencyInfo correct with unified gesture detector on Aura.

BUG=379812
TEST=GestureRecognizerTest.LatencyPassedFromTouchEvent

Review URL: https://codereview.chromium.org/309823002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@274602 0039d316-1c4b-4281-b951-d872f2087c98
   const gfx::Rect& bounding_box() const { return bounding_box_; }

   const gfx::Rect& bounding_box() const { return bounding_box_; }
