Ensure navigator.language agrees with navigator.languages

Although perhaps not strictly required by the specification, it is at least
quite clearly suggested that navigator.language should equal the first element
of navigator.languages (see note in [1]).

[1]: https://html.spec.whatwg.org/multipage/system-state.html#language-preferences

Changes in behavior:

  - navigator.language:

    Previously returned DefaultLanguage() which may or may not have matched the
    first element of navigator.languages.

    Now always returns the first element from navigator.languages.

  - navigator.languages:

    Previously would return an empty list if ChromeClient's AcceptLanguages()
    happened to return an empty string.

    Now always returns a non-empty list (the existing DefaultLanguage() fallback
    is extended to cover this case too).

Bug: 351715
Change-Id: Id945ec3958180991c0abcfec4e5c191d3cb5e9cf
Reviewed-on: https://chromium-review.googlesource.com/581295
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521394}

AUTHORS

@@ -419,6 +419,7 @@ JungJik Lee <jungjik.lee@samsung.com>
 Jungkee Song <jungkee.song@samsung.com>
 Junmin Zhu <junmin.zhu@intel.com>
 Justin Okamoto <justmoto@amazon.com>
+Jüri Valdmann <juri.valdmann@qt.io>
 Kai Jiang <jiangkai@gmail.com>
 Kai Köhne <kai.koehne@qt.io>
 Kal Conley <kcconley@gmail.com>

third_party/WebKit/LayoutTests/navigator_language/navigator_language.html

@@ -90,16 +90,16 @@
 
 test(function() {
     var testValues = [
-        { accept_languages: 'foo', language: 'foo', languages: ['foo'] },
-        { accept_languages: '', language: '', languages: [] },
-        { accept_languages: 'foo,bar', language: 'foo', languages: [ 'foo', 'bar' ] },
-        { accept_languages: '  foo , bar ', language: 'foo', languages: [ 'foo', 'bar' ] },
-        { accept_languages: '  foo ; bar ', language: 'foo ; bar', languages: [ 'foo ; bar' ] },
-        { accept_languages: '_foo_', language: '_foo_', languages: ['_foo_'] },
-        { accept_languages: 'en_', language: 'en-', languages: ['en-'] },
-        { accept_languages: 'en__', language: 'en-_', languages: ['en-_'] },
-        { accept_languages: 'en_US, fr_FR', language: 'en-US', languages: ['en-US', 'fr-FR'] },
-        { accept_languages: 'en_US_CA', language: 'en-US_CA', languages: ['en-US_CA'] },
+        { accept_languages: 'foo', languages: ['foo'] },
+        { accept_languages: '', languages: ['en-US'] },
+        { accept_languages: 'foo,bar', languages: [ 'foo', 'bar' ] },
+        { accept_languages: '  foo , bar ', languages: [ 'foo', 'bar' ] },
+        { accept_languages: '  foo ; bar ', languages: [ 'foo ; bar' ] },
+        { accept_languages: '_foo_', languages: ['_foo_'] },
+        { accept_languages: 'en_', languages: ['en-'] },
+        { accept_languages: 'en__', languages: ['en-_'] },
+        { accept_languages: 'en_US, fr_FR', languages: ['en-US', 'fr-FR'] },
+        { accept_languages: 'en_US_CA', languages: ['en-US_CA'] },
     ];
 
     var eventsCount = 0;
@@ -114,7 +114,7 @@
         assert_equals(eventsCount, i + 1);
 
         assert_equals(navigator.languages.length, data.languages.length);
-        // FIXME: test navigator.language
+        assert_equals(navigator.language, data.languages[0]);
         for (var j = 0; j < navigator.languages.length; ++j) {
             assert_equals(navigator.languages[j], data.languages[j]);
         }
@@ -130,11 +130,6 @@
     assert_not_equals(navigator.languages, previous);
 }, "Test navigator.languages' caching behaviour.");
 
-test(function() {
-    // The region code should be uppercase.
-    assert_equals(navigator.language, 'en-US');
-}, 'Test the default navigator.language in the test environment.');
-
 </script>
 </body>
 </html>

third_party/WebKit/Source/core/frame/Navigator.cpp

@@ -88,16 +88,15 @@ bool Navigator::cookieEnabled() const {
 }
 
 Vector<String> Navigator::languages() {
-  Vector<String> languages;
   languages_changed_ = false;
 
-  if (!GetFrame() || !GetFrame()->GetPage()) {
-    languages.push_back(DefaultLanguage());
-    return languages;
+  String accept_languages;
+  if (GetFrame() && GetFrame()->GetPage()) {
+    accept_languages =
+        GetFrame()->GetPage()->GetChromeClient().AcceptLanguages();
   }
 
-  String accept_languages =
-      GetFrame()->GetPage()->GetChromeClient().AcceptLanguages();
+  Vector<String> languages;
   accept_languages.Split(',', languages);
 
   // Sanitizing tokens. We could do that more extensively but we should assume
@@ -110,6 +109,9 @@ Vector<String> Navigator::languages() {
       token.replace(2, 1, "-");
   }
 
+  if (languages.IsEmpty())
+    languages.push_back(DefaultLanguage());
+
   return languages;
 }
 

third_party/WebKit/Source/core/frame/NavigatorLanguage.cpp

@@ -11,7 +11,7 @@ namespace blink {
 NavigatorLanguage::NavigatorLanguage() {}
 
 AtomicString NavigatorLanguage::language() {
-  return DefaultLanguage();
+  return AtomicString(languages().front());
 }
 
 bool NavigatorLanguage::hasLanguagesChanged() const {