Null out gainmaps on inBitmap re-use

Bug: 277230526
Test: android.graphics.cts.GainmapTest#testDecodeGainmapBitmapFactoryReuse
Change-Id: I437f2599f023d83bdd70f1bf123357318c79b4e3

graphics/java/android/graphics/Bitmap.java

@@ -1921,6 +1921,7 @@ public final class Bitmap implements Parcelable {
      */
     public void setGainmap(@Nullable Gainmap gainmap) {
         checkRecycled("Bitmap is recycled");
+        mGainmap = null;
         nativeSetGainmap(mNativePtr, gainmap == null ? 0 : gainmap.mNativePtr);
     }
 

graphics/java/android/graphics/BitmapFactory.java

@@ -482,7 +482,9 @@ public class BitmapFactory {
             if (opts == null || opts.inBitmap == null) {
                 return 0;
             }
-
+            // Clear out the gainmap since we don't attempt to reuse it and don't want to
+            // accidentally keep it on the re-used bitmap
+            opts.inBitmap.setGainmap(null);
             return opts.inBitmap.getNativeInstance();
         }