Fix conversion from String to Blob in ClipboardItem.getType()

String::Span8() does not return UTF-8 encoded data, but rather Latin-1
if the string has an 8-bit backing. If the string has a 16-bit backing
it returns jibberish.

Fixed: 457303645
Change-Id: Ibce8f4817b6e8571baf041867065da7eb13a9b23
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7110225
Auto-Submit: Fredrik Söderquist <[email protected]>
Reviewed-by: Daniel Cheng <[email protected]>
Commit-Queue: Daniel Cheng <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1539397}

Author: Fredrik Söderquist

clipboard-apis/async-navigator-clipboard-write-domstring.https.html

@@ -95,6 +95,21 @@
     assert_true(blob instanceof Blob, "item.getType('text/html') should return a Blob");
   }, 'validate GetType(type) on a constructed ClipboardItem returns Blob');
 
+  promise_test(async () => {
+    await getPermissions();
+    // Test string with various non-Latin characters: Chinese, Arabic, Cyrillic, emoji
+    const nonLatinText = "你好 مرحبا Привет 👋🌍";
+    const item = new ClipboardItem({
+      'text/plain': nonLatinText
+    });
+    const textBlob = await item.getType('text/plain');
+
+    // Read back the text and verify it matches
+    const readText = await textBlob.text();
+    assert_equals(readText, nonLatinText,
+      "Text read from ClipboardItem should match the non-Latin text that was written");
+  }, 'write non-Latin characters with DOMString and verify getType returns a Blob with the same string');
+
   promise_test(async () => {
     await getPermissions();
     // Test string with various non-Latin characters: Chinese, Arabic, Cyrillic, emoji