Reset stored background resource when setting a bg color

This sequence of operations would prevent the background from
changing:

setBackgroundResource(R.something)
setBackgroundColor(aColor)
setBackgroundResource(R.something)

The last call would be no-oped.

Change-Id: I436a33599c88e35f6f36bdd63e9c256c9219e052
diff --git a/core/java/android/view/View.java b/core/java/android/view/View.java
index 7799bb9..181fce9 100644
--- a/core/java/android/view/View.java
+++ b/core/java/android/view/View.java
@@ -14465,6 +14465,7 @@
         if (mBackground instanceof ColorDrawable) {
             ((ColorDrawable) mBackground.mutate()).setColor(color);
             computeOpaqueFlags();
+            mBackgroundResource = 0;
         } else {
             setBackground(new ColorDrawable(color));
         }