Remove unused field.

This issue was found by a linter.

R=vollick@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/23523027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221314 0039d316-1c4b-4281-b951-d872f2087c98

ui/compositor/layer_animator_unittest.cc

@@ -112,7 +112,6 @@ class DeletingLayerAnimationObserver : public LayerAnimationObserver {
 
  private:
   LayerAnimator* animator_;
-  LayerAnimationSequence* sequence_;
 
   DISALLOW_COPY_AND_ASSIGN(DeletingLayerAnimationObserver);
 };