Add dither XML flag to StateListDrawable.

We currently allow the dither="true" flag to be set on
individual <bitmap> and <nine-patch> objects, but that flag
is overridden when they are included in a <selector>.  This
change adds the dither="true" flag to StateListDrawable so
they can be dithered when desired.

Fixes http://b/issue?id=2068024

core/res/res/values/attrs.xml

@@ -2274,6 +2274,10 @@
              of the states.  If false, the size will vary based on the
              current state. -->
         <attr name="constantSize" format="boolean" />
+        <!-- Enables or disables dithering of the bitmap if the bitmap does not have the
+             same pixel configuration as the screen (for instance: a ARGB 8888 bitmap with
+             an RGB 565 screen.) -->
+        <attr name="dither" format="boolean" />
     </declare-styleable>
 
     <declare-styleable name="AnimationDrawable">
@@ -2420,7 +2424,7 @@
         <!-- Enables or disables dithering of the bitmap if the bitmap does not have the
              same pixel configuration as the screen (for instance: a ARGB 8888 bitmap with
              an RGB 565 screen.) -->
-        <attr name="dither" format="boolean" />
+        <attr name="dither" />
         <!-- Defines the gravity for the bitmap. The gravity indicates where to position
              the drawable in its container if the bitmap is smaller than the container. -->
         <attr name="gravity" />

graphics/java/android/graphics/drawable/StateListDrawable.java

@@ -105,6 +105,8 @@ public class StateListDrawable extends DrawableContainer {
         mStateListState.setConstantSize(a.getBoolean(
                 com.android.internal.R.styleable.StateListDrawable_constantSize, false));
 
+        setDither(a.getBoolean(com.android.internal.R.styleable.StateListDrawable_dither, false));
+
         a.recycle();
 
         int type;