FloatingActionButton.Behavior をカスタムして使ってみる ref: http://qiita.com/eccyan/items/cbfce9e94f81ecfaa452

file0.java

public class AwesomeView extends ViewGroup {
    public static class FabBehavior extends FloatingActionButton.Behavior {

        private AwesomeView mAwesomeView;

        public FabBehavior() {
        }

        public FabBehavior(Context context, AttributeSet attrs) {
        }

        @Override
        public boolean layoutDependsOn(CoordinatorLayout parent, FloatingActionButton child,
                View dependency) {
            mAwesomeView = findAwesomeView(dependency);
            return mAwesomeView != null || super.layoutDependsOn(parent, child, dependency);
        }

        @Override
        public boolean onDependentViewChanged(CoordinatorLayout parent, FloatingActionButton child,
                View dependency) {
            if (mAwesomeView != null) {
                updateFabTranslationForAwesomeView(parent, child, mAwesomeView);
            }

            return super.onDependentViewChanged(parent, child, dependency);
        }

        private void updateFabTranslationForAwesomeView(CoordinatorLayout parent,
                FloatingActionButton fab, View awesomeView) {
            float translationY = this.getFabTranslationYForAwesomeView(parent, fab);
            if (translationY != this.mTranslationY) {
                ViewCompat.animate(fab).cancel();
                if (Math.abs(translationY - this.mTranslationY) == (float) awesomeView.getHeight()) {
                    ViewCompat.animate(fab)
                            .translationY(translationY)
                            .setInterpolator(INTERPOLATOR)
                            .setListener(null);
                } else {
                    ViewCompat.setTranslationY(fab, translationY);
                }

                this.mTranslationY = translationY;
            }

        }

        private float getFabTranslationYForAwesomeView(CoordinatorLayout parent,
                FloatingActionButton fab) {
            final float offset = (mAwesomeView == null) ? .0f
                    : ViewCompat.getTranslationY(mAwesomeView) - (float) mAwesomeView.getHeight();
            return Math.min(.0f, offset);
        }

        // TODO: 複数の AwesomeView 対応できるように
        private AwesomeView findAwesomeView(View view) {
            if (view instanceof AwesomeView) {
                return (AwesomeView) view;
            } else if (view instanceof ViewGroup) {
                final ViewGroup group = (ViewGroup) view;
                for (int i = 0; i < group.getChildCount(); ++i) {
                    final AwesomeView awesomeView = findAwesomeView(group.getChildAt(i));
                    if (awesomeView != null) {
                        return awesomeView;
                    }
                }
            }

            return null;
        }
    }
}