Remove color attribute from MaskableIconDrawable foreground/background tag

Test: manual test

Change-Id: Ia8426051aed8c4451b10cf415e179930caede974

core/res/res/values/attrs.xml

@@ -5846,8 +5846,6 @@
 
     <!-- Drawable used to draw masked icons with foreground and background layers. -->
     <declare-styleable name="MaskableIconDrawableLayer">
-        <!-- The color to use for the layer, only if drawable is not defined. -->
-        <attr name="color" />
         <!-- The drawable to use for the layer. -->
         <attr name="drawable" />
      </declare-styleable>

graphics/java/android/graphics/drawable/MaskableIconDrawable.java

@@ -427,7 +427,7 @@ public class MaskableIconDrawable extends Drawable implements Drawable.Callback
                 }
                 if (type != XmlPullParser.START_TAG) {
                     throw new XmlPullParserException(parser.getPositionDescription()
-                            + ": <foreground> or <background> tag requires a 'color' or 'drawable'"
+                            + ": <foreground> or <background> tag requires a 'drawable'"
                             + "attribute or child tag defining a drawable");
                 }
 
@@ -451,12 +451,6 @@ public class MaskableIconDrawable extends Drawable implements Drawable.Callback
         layer.mThemeAttrs = a.extractThemeAttrs();
 
         Drawable dr = a.getDrawable(R.styleable.MaskableIconDrawableLayer_drawable);
-        if (dr == null) {
-             int color = a.getColor(R.styleable.MaskableIconDrawableLayer_color, Color.TRANSPARENT);
-             if (color != Color.TRANSPARENT) {
-                 dr = new ColorDrawable(color);
-             }
-        }
         if (dr != null) {
             if (layer.mDrawable != null) {
                 // It's possible that a drawable was already set, in which case