RemoteViews: make bitmaps immutable

Because mutability is propagated across Parcel and Binder, any mutable
Bitmaps passed to RemoteViews will end up mutable on the other side
even though those Bitmaps can't be modified from the RemoteViews
recipient.

Make all Bitmaps passed to RemoteViews immutable in order to ensure
that they can be sent without additional copies instead of the one
ashmem object.

Test: TH, RemoteViews work for widgets
Bug: 227920378

Change-Id: I477e7132f9ff78333c1eda56b9d0fc6ac520abd0

core/java/android/widget/RemoteViews.java

@@ -1588,24 +1588,33 @@ public class RemoteViews implements Parcelable, Filter {
 
         @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
         ArrayList<Bitmap> mBitmaps;
+        SparseIntArray mBitmapHashes;
         int mBitmapMemory = -1;
 
         public BitmapCache() {
             mBitmaps = new ArrayList<>();
+            mBitmapHashes = new SparseIntArray();
         }
 
         public BitmapCache(Parcel source) {
             mBitmaps = source.createTypedArrayList(Bitmap.CREATOR);
+            mBitmapHashes = source.readSparseIntArray();
         }
 
         public int getBitmapId(Bitmap b) {
             if (b == null) {
                 return -1;
             } else {
-                if (mBitmaps.contains(b)) {
-                    return mBitmaps.indexOf(b);
+                int hash = b.hashCode();
+                int hashId = mBitmapHashes.get(hash, -1);
+                if (hashId != -1) {
+                    return hashId;
                 } else {
+                    if (b.isMutable()) {
+                        b = b.asShared();
+                    }
                     mBitmaps.add(b);
+                    mBitmapHashes.put(mBitmaps.size() - 1, hash);
                     mBitmapMemory = -1;
                     return (mBitmaps.size() - 1);
                 }
@@ -1616,13 +1625,13 @@ public class RemoteViews implements Parcelable, Filter {
         public Bitmap getBitmapForId(int id) {
             if (id == -1 || id >= mBitmaps.size()) {
                 return null;
-            } else {
-                return mBitmaps.get(id);
             }
+            return mBitmaps.get(id);
         }
 
         public void writeBitmapsToParcel(Parcel dest, int flags) {
             dest.writeTypedList(mBitmaps, flags);
+            dest.writeSparseIntArray(mBitmapHashes);
         }
 
         public int getBitmapMemory() {