Make BitmapDrawable#setBitmap public

Bug: 154628299
Test: I20d4f94a145474394bc660368d9ddd1897001f4a

This allows displaying a new Bitmap without paying the cost of creation
and GC of the BitmapDrawable.

Non-SDK-API usage is low, but this is useful. Previously it was @hide
and used by the system. Once BitmapDrawable is in a mainline module,
the system can no longer access @hide methods.

Change-Id: I6a24b3c5870b0ee7d171aab86257896261b4b8c7

api/current.txt

@@ -15784,6 +15784,7 @@ package android.graphics.drawable {
     method public final boolean isAutoMirrored();
     method public void setAlpha(int);
     method public void setAntiAlias(boolean);
+    method public void setBitmap(@Nullable android.graphics.Bitmap);
     method public void setColorFilter(android.graphics.ColorFilter);
     method public void setDither(boolean);
     method public void setGravity(int);

graphics/java/android/graphics/drawable/BitmapDrawable.java

@@ -17,6 +17,7 @@
 package android.graphics.drawable;
 
 import android.annotation.NonNull;
+import android.annotation.Nullable;
 import android.compat.annotation.UnsupportedAppUsage;
 import android.content.pm.ActivityInfo.Config;
 import android.content.res.ColorStateList;
@@ -239,9 +240,10 @@ public class BitmapDrawable extends Drawable {
         }
     }
 
-    /** @hide */
-    @UnsupportedAppUsage
-    public void setBitmap(Bitmap bitmap) {
+    /**
+     * Switch to a new Bitmap object.
+     */
+    public void setBitmap(@Nullable Bitmap bitmap) {
         if (mBitmapState.mBitmap != bitmap) {
             mBitmapState.mBitmap = bitmap;
             computeBitmapSize();