webnn: Discard data when canceling a BYOB read

If the buffer is detached the read is cancelled however the data in the
shared Mojo data pipe used for reads still need to be handled or else a
later read will get this data instead.

Fixed: 511826204
Change-Id: I82f10690d741c8b9b34419c3ac3d0e85511fd594
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7858250
Reviewed-by: Hu, Ningxin <ningxin.hu@intel.com>
Commit-Queue: Reilly Grant <reillyg@chromium.org>
Auto-Submit: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1633293}

Author: reillyeon

webnn/conformance_tests/byob_readtensor.https.any.js

@@ -195,3 +195,37 @@ promise_test(async (t) => {
 
   await checks;
 }, `readTensor() rejects when the MLTensor is destroyed`);
+
+promise_test(async (t) => {
+  const tensorA = await mlContext.createTensor({
+    dataType: 'int32',
+    shape: [128, 1024],
+    readable: true,
+    writable: true,
+  });
+  const tensorB = await mlContext.createTensor({
+    dataType: 'int32',
+    shape: [128, 1024],
+    readable: true,
+    writable: true,
+  });
+  const length = tensorA.shape.reduce((a, b) => a * b);
+  const contentsA = new Int32Array(length).fill(1);
+  const contentsB = new Int32Array(length).fill(2);
+
+  mlContext.writeTensor(tensorA, contentsA);
+  mlContext.writeTensor(tensorB, contentsB);
+
+  const bufferA = new ArrayBuffer(contentsA.byteLength);
+  const readPromise = mlContext.readTensor(tensorA, bufferA);
+  bufferA.transfer();
+
+  await promise_rejects_js(t, TypeError, readPromise);
+
+  const bufferB = new ArrayBuffer(contentsB.byteLength);
+  await mlContext.readTensor(tensorB, bufferB);
+  assert_array_equals(new Int32Array(bufferB), contentsB);
+
+  tensorA.destroy();
+  tensorB.destroy();
+}, `Subsequent readTensor() after reading into a detached buffer gets correct data`);