Fixing MainThreadInitializedObject

> Making SafeCloseable implementation mandatory, to prevent leaks during test and preview
> Removing getNoCreate method and defining executeIfCreated to avoid null pointer exceptions
> Fixing sandbox value leaking into main, by Checking sandbox against App context
> Converting sanbox to an interface instead a class

Bug: 335280439
Test: Presubmit
Flag: None
Change-Id: I951dcde871898e745ff6490a1c4f8fd1512888f5

src/com/android/launcher3/util/DynamicResource.java

@@ -33,7 +33,8 @@ import com.android.systemui.plugins.ResourceProvider;
  *
  * To allow customization for a particular resource, add them to dynamic_resources.xml
  */
-public class DynamicResource implements ResourceProvider, PluginListener<ResourceProvider> {
+public class DynamicResource implements
+        ResourceProvider, PluginListener<ResourceProvider>, SafeCloseable {
 
     private static final MainThreadInitializedObject<DynamicResource> INSTANCE =
             new MainThreadInitializedObject<>(DynamicResource::new);
@@ -47,6 +48,11 @@ public class DynamicResource implements ResourceProvider, PluginListener<Resourc
                 ResourceProvider.class, false /* allowedMultiple */);
     }
 
+    @Override
+    public void close() {
+        PluginManagerWrapper.INSTANCE.get(mContext).removePluginListener(this);
+    }
+
     @Override
     public int getInt(@IntegerRes int resId) {
         return mContext.getResources().getInteger(resId);