Add "close()" method to MP Web Tasks

PiperOrigin-RevId: 527726737

mediapipe/web/graph_runner/graph_runner.ts

@@ -63,6 +63,7 @@ export declare interface WasmModule {
   _bindTextureToCanvas: () => boolean;
   _changeBinaryGraph: (size: number, dataPtr: number) => void;
   _changeTextGraph: (size: number, dataPtr: number) => void;
+  _closeGraph: () => void;
   _free: (ptr: number) => void;
   _malloc: (size: number) => number;
   _processFrame: (width: number, height: number, timestamp: number) => void;
@@ -1148,6 +1149,16 @@ export class GraphRunner {
   finishProcessing(): void {
     this.wasmModule._waitUntilIdle();
   }
+
+  /**
+   * Closes the input streams and all calculators for this graph and frees up
+   * any C++ resources. The graph will not be usable once closed.
+   */
+  closeGraph(): void {
+    this.wasmModule._closeGraph();
+    this.wasmModule.simpleListeners = undefined;
+    this.wasmModule.emptyPacketListeners = undefined;
+  }
 }
 
 // Quick private helper to run the given script safely