Support passing IOHandler to model urls of selfie_segmentation (#935)

Author: ahmedsabie

body-segmentation/src/selfie_segmentation_tfjs/README.md

@@ -69,7 +69,10 @@ Pass in `bodySegmentation.SupportedModels.MediaPipeSelfieSegmentation` from the
     'general', 'landscape'). If unset, the default is 'general'.
 
 *   *modelUrl*: An optional string that specifies custom url of
-the segmentation model. This is useful for area/countries that don't have access to the model hosted on tf.hub.
+the segmentation model. This is useful for area/countries that don't have access to the model hosted on tf.hub. It also accepts `io.IOHandler` which can be used with
+[tfjs-react-native](https://github.com/tensorflow/tfjs/tree/master/tfjs-react-native)
+to load model from app bundle directory using
+[bundleResourceIO](https://github.com/tensorflow/tfjs/blob/master/tfjs-react-native/src/bundle_resource_io.ts#L169).
 
 ```javascript
 const model = bodySegmentation.SupportedModels.MediaPipeSelfieSegmentation;

body-segmentation/src/selfie_segmentation_tfjs/segmenter.ts

@@ -160,7 +160,8 @@ export async function load(
     Promise<BodySegmenter> {
   const config = validateModelConfig(modelConfig);
 
-  const modelFromTFHub = (config.modelUrl.indexOf('https://tfhub.dev') > -1);
+  const modelFromTFHub = typeof config.modelUrl === 'string' &&
+      (config.modelUrl.indexOf('https://tfhub.dev') > -1);
 
   const model =
       await tfconv.loadGraphModel(config.modelUrl, {fromTFHub: modelFromTFHub});

body-segmentation/src/selfie_segmentation_tfjs/types.ts

@@ -15,6 +15,7 @@
  * =============================================================================
  */
 
+import {io} from '@tensorflow/tfjs-core';
 import {MediaPipeSelfieSegmentationModelConfig, MediaPipeSelfieSegmentationSegmentationConfig} from '../selfie_segmentation_mediapipe/types';
 
 /**
@@ -35,7 +36,7 @@ import {MediaPipeSelfieSegmentationModelConfig, MediaPipeSelfieSegmentationSegme
 export interface MediaPipeSelfieSegmentationTfjsModelConfig extends
     MediaPipeSelfieSegmentationModelConfig {
   runtime: 'tfjs';
-  modelUrl?: string;
+  modelUrl?: string|io.IOHandler;
 }
 
 /**