[FS] Require a leading . in accepted extensions.

Implements the changes from https://github.com/WICG/native-file-system/pull/219.

Change-Id: Ic785f0362b5c73a843145c5384f063cf24770b7b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2360597
Commit-Queue: Victor Costan <pwnall@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799617}

content/browser/native_file_system/file_system_chooser_browsertest.cc

@@ -583,9 +583,9 @@ IN_PROC_BROWSER_TEST_F(FileSystemChooserBrowserTest, AcceptsOptions) {
   auto result =
       EvalJs(shell(),
              "self.showOpenFilePicker({types: ["
-             "  {description: 'foo', accept: {'text/custom': ['txt', 'Js']}},"
+             "  {description: 'foo', accept: {'text/custom': ['.txt', '.Js']}},"
              "  {accept: {'image/jpeg': []}},"
-             "  {accept: {'image/svg+xml': 'svg'}},"
+             "  {accept: {'image/svg+xml': '.svg'}},"
              "]})");
   EXPECT_TRUE(result.error.find("aborted") != std::string::npos)
       << result.error;

third_party/blink/renderer/modules/native_file_system/global_native_file_system.cc

@@ -71,6 +71,18 @@ constexpr bool IsHTTPWhitespace(UChar chr) {
   return chr == ' ' || chr == '\n' || chr == '\t' || chr == '\r';
 }
 
+bool AddExtension(const String& extension,
+                  Vector<String>& extensions,
+                  ExceptionState& exception_state) {
+  if (!extension.StartsWith(".")) {
+    exception_state.ThrowTypeError("Extension '" + extension +
+                                   "' must start with '.'.");
+    return false;
+  }
+  extensions.push_back(extension.Substring(1));
+  return true;
+}
+
 Vector<mojom::blink::ChooseFileSystemEntryAcceptsOptionPtr> ConvertAccepts(
     const HeapVector<Member<FilePickerAcceptType>>& types,
     ExceptionState& exception_state) {
@@ -102,10 +114,16 @@ Vector<mojom::blink::ChooseFileSystemEntryAcceptsOptionPtr> ConvertAccepts(
       }
 
       mimeTypes.push_back(type);
-      if (a.second.IsUSVString())
-        extensions.push_back(a.second.GetAsUSVString());
-      else
-        extensions.AppendVector(a.second.GetAsUSVStringSequence());
+      if (a.second.IsUSVString()) {
+        if (!AddExtension(a.second.GetAsUSVString(), extensions,
+                          exception_state))
+          return {};
+      } else {
+        for (const auto& extension : a.second.GetAsUSVStringSequence()) {
+          if (!AddExtension(extension, extensions, exception_state))
+            return {};
+        }
+      }
     }
     result.emplace_back(
         blink::mojom::blink::ChooseFileSystemEntryAcceptsOption::New(

third_party/blink/web_tests/external/wpt/native-file-system/showOpenFilePicker-manual.https.html

@@ -21,8 +21,8 @@
       'show a file picker.<br />Please select native-file-system/resources/data/testfile.txt');
     const files = await self.showOpenFilePicker({
       multiple: false, types: [
-        { description: 'Text files', accept: { ' text/plain ': ['txt'] } },
-        { description: 'Images', accept: { '  image/*  ': ['jpg', 'jpeg', 'png'] } },
+        { description: 'Text files', accept: { ' text/plain ': ['.txt'] } },
+        { description: 'Images', accept: { '  image/*  ': ['.jpg', '.jpeg', '.png'] } },
       ],
     });
     assert_true(Array.isArray(files));

third_party/blink/web_tests/external/wpt/native-file-system/showPicker-errors.https.window.js

@@ -27,47 +27,47 @@ function define_file_picker_error_tests(showPickerMethod) {
   promise_test(async t => {
     await promise_rejects_js(
         t, TypeError,
-        self[showPickerMethod]({types: [{accept: {'': ['foo']}}]}));
+        self[showPickerMethod]({types: [{accept: {'': ['.foo']}}]}));
     await promise_rejects_js(
         t, TypeError,
-        self[showPickerMethod]({types: [{accept: {'  ': ['foo']}}]}));
+        self[showPickerMethod]({types: [{accept: {'  ': ['.foo']}}]}));
   }, showPickerMethod + ': MIME type can\'t be an empty string.');
 
   promise_test(async t => {
     await promise_rejects_js(
         t, TypeError,
-        self[showPickerMethod]({types: [{accept: {'image': ['foo']}}]}));
+        self[showPickerMethod]({types: [{accept: {'image': ['.foo']}}]}));
   }, showPickerMethod + ': MIME type must have subtype.');
 
   promise_test(async t => {
     await promise_rejects_js(
         t, TypeError,
-        self[showPickerMethod]({types: [{accept: {'  /plain': ['foo']}}]}));
+        self[showPickerMethod]({types: [{accept: {'  /plain': ['.foo']}}]}));
   }, showPickerMethod + ': MIME type can\'t have empty type.');
 
   promise_test(async t => {
     await promise_rejects_js(
         t, TypeError,
-        self[showPickerMethod]({types: [{accept: {'image/  ': ['foo']}}]}));
+        self[showPickerMethod]({types: [{accept: {'image/  ': ['.foo']}}]}));
   }, showPickerMethod + ': MIME type can\'t have empty subtype.');
 
   promise_test(async t => {
     await promise_rejects_js(
         t, TypeError,
         self[showPickerMethod](
-            {types: [{accept: {'text/plain;charset=utf8': ['txt']}}]}));
+            {types: [{accept: {'text/plain;charset=utf8': ['.txt']}}]}));
   }, showPickerMethod + ': MIME type can\'t have parameters.');
 
   promise_test(async t => {
     await promise_rejects_js(t, TypeError, self[showPickerMethod]({
-                               types: [{accept: {'text>foo/plain': ['txt']}}]
+                               types: [{accept: {'text>foo/plain': ['.txt']}}]
                              }));
   }, showPickerMethod + ': MIME type can\'t have invalid characters in type.');
 
   promise_test(async t => {
     await promise_rejects_js(
         t, TypeError,
-        self[showPickerMethod]({types: [{accept: {'text / plain': ['txt']}}]}));
+        self[showPickerMethod]({types: [{accept: {'text / plain': ['.txt']}}]}));
   }, showPickerMethod + ': MIME type can\'t have whitespace in the middle.');
 
   promise_test(
@@ -75,8 +75,14 @@ function define_file_picker_error_tests(showPickerMethod) {
         await promise_rejects_js(
             t, TypeError,
             self[showPickerMethod](
-                {types: [{accept: {'text/plain>foo': ['txt']}}]}));
+                {types: [{accept: {'text/plain>foo': ['.txt']}}]}));
       },
       showPickerMethod +
           ': MIME type can\'t have invalid characters in subtype.');
-}
+
\ No newline at end of file
+  promise_test(async t => {
+    await promise_rejects_js(t, TypeError, self[showPickerMethod]({
+                               types: [{accept: {'text/plain': ['.txt', 'txt']}}]
+                             }));
+  }, showPickerMethod + ': extension has to start with ".".');
+}

third_party/blink/web_tests/external/wpt/native-file-system/showSaveFilePicker-manual.https.html

@@ -14,7 +14,7 @@
       'show a file picker.<br />Please make a copy of native-file-system/resources/data/testfile.txt in a writable directory and pick that file');
     const file = await self.showSaveFilePicker({
       multiple: false, types: [
-        { description: 'Text files', accept: { 'text/plain': ['txt'] } },
+        { description: 'Text files', accept: { 'text/plain': ['.txt'] } },
       ],
     });
     assert_true(file instanceof FileSystemHandle);