Update local state when creating LayerDrawable from constant state

Also clears DrawableContainer's futures list when it's no longer needed,
correctly sets deep copy of state set in StateListDrawable, makes some
private methods into package-protected to avoid thunk, and propagates
state to StateListDrawable's super class so that getState() has correct
information.

Bug: 21840003
Change-Id: I0d4232807f280d663c03b4a80e4aab8626806440

graphics/java/android/graphics/drawable/DrawableContainer.java

@@ -730,7 +730,7 @@ public class DrawableContainer extends Drawable implements Drawable.Callback {
                 if (origDf != null) {
                     mDrawableFutures = origDf.clone();
                 } else {
-                    mDrawableFutures = new SparseArray<ConstantStateFuture>(mNumChildren);
+                    mDrawableFutures = new SparseArray<>(mNumChildren);
                 }
 
                 // Create futures for drawables with constant states. If a
@@ -823,6 +823,9 @@ public class DrawableContainer extends Drawable implements Drawable.Callback {
                     final Drawable prepared = mDrawableFutures.valueAt(keyIndex).get(this);
                     mDrawables[index] = prepared;
                     mDrawableFutures.removeAt(keyIndex);
+                    if (mDrawableFutures.size() == 0) {
+                        mDrawableFutures = null;
+                    }
                     return prepared;
                 }
             }