Translator: Don't initiate model download if CreateMonitorCallback throws

If the CreateMonitorCallback throws an error, then model download
should not be initiated.

Fixed: 409861269
Change-Id: Ib9f09aad91b431ff9b3a5c77df777c4df7f60997
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6598914
Commit-Queue: Nathan Memmott <[email protected]>
Reviewed-by: Daseul Lee <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1470158}

Author: Nathan Memmott

ai/language_detection/detector.https.window.js

@@ -66,16 +66,7 @@ promise_test(async t => {
 }, 'LanguageDetector.detect() returns valid results');
 
 promise_test(async t => {
-  const error = new Error('CreateMonitorCallback threw an error');
-  function monitor(m) {
-    m.addEventListener('downloadprogress', e => {
-      assert_unreached(
-          'This should never be reached since monitor throws an error.');
-    });
-    throw error;
-  }
-
-  await promise_rejects_exactly(t, error, createLanguageDetector({monitor}));
+  await testCreateMonitorCallbackThrowsError(t, createLanguageDetector);
 }, 'If monitor throws an error, LanguageDetector.create() rejects with that error');
 
 promise_test(async t => {

ai/resources/util.js

@@ -182,6 +182,20 @@ async function testMonitor(createFunc, options = {}) {
   return result;
 }
 
+async function testCreateMonitorCallbackThrowsError(
+    t, createFunc, options = {}) {
+  const error = new Error('CreateMonitorCallback threw an error');
+  function monitor(m) {
+    m.addEventListener('downloadprogress', e => {
+      assert_unreached(
+          'This should never be reached since monitor throws an error.');
+    });
+    throw error;
+  }
+
+  await promise_rejects_exactly(t, error, createFunc({...options, monitor}));
+}
+
 function run_iframe_test(iframe, test_name) {
   const id = getId();
   iframe.contentWindow.postMessage({id, type: test_name}, '*');

ai/translator/translator.https.window.js

@@ -0,0 +1,16 @@
+// META: title=Translator tests
+// META: global=window
+// META: timeout=long
+// META: script=../resources/util.js
+// META: script=/resources/testdriver.js
+// META: script=resources/util.js
+//
+// Setting `timeout=long` as this test may require downloading the translation
+// library and the language models.
+
+promise_test(async t => {
+  // Can pass in valid but unsupported languages since the create monitor error
+  // should be thrown before language support is checked.
+  await testCreateMonitorCallbackThrowsError(
+      t, createTranslator, {sourceLanguage: 'und', targetLanguage: 'und'});
+}, 'If monitor throws an error, LanguageDetector.create() rejects with that error');

ai/translator/translator.optional.https.window.js

@@ -1,8 +1,7 @@
-// META: title=Translator Translate
+// META: title=Optional Translator tests
 // META: global=window
 // META: timeout=long
 // META: script=../resources/util.js
-// META: script=../resources/language_codes.js
 // META: script=/resources/testdriver.js
 // META: script=resources/util.js
 //