Finalize and delete a counter metric

glean-core/android/src/main/java/mozilla/telemetry/glean/private/CounterMetricType.kt

@@ -9,6 +9,7 @@ import com.sun.jna.StringArray
 import mozilla.telemetry.glean.Glean
 import mozilla.telemetry.glean.rust.LibGleanFFI
 import mozilla.telemetry.glean.rust.toByte
+import mozilla.telemetry.glean.rust.RustError
 
 import mozilla.telemetry.glean.Dispatchers
 import mozilla.telemetry.glean.rust.toBoolean
@@ -50,6 +51,13 @@ class CounterMetricType(
                 disabled = disabled.toByte())
     }
 
+    protected fun finalize() {
+        if (this.handle != 0L) {
+            val error = RustError.ByReference()
+            LibGleanFFI.INSTANCE.glean_destroy_counter_metric(this.handle, error)
+        }
+    }
+
     /**
      * Add to counter value.
      *