From 1f69a14621f5b2d30a2dde48b095c5dcf21312c3 Mon Sep 17 00:00:00 2001
From: Zeke Medley <zekemedley@gmail.com>
Date: Mon, 17 Aug 2020 01:41:16 +0000
Subject: [PATCH] Bug 1658780 - Update the prefers-contrast media query to use
 the new more/less keywords r=emilio

Per the resolution here:
https://github.com/w3c/csswg-drafts/issues/2943#issuecomment-672994920

Differential Revision: https://phabricator.services.mozilla.com/D86848
---
 .../high-contrast/prefers-contrast-002.html     |  2 +-
 layout/style/nsMediaFeatures.cpp                |  2 +-
 .../chrome/test_chrome_only_media_queries.html  |  4 ++--
 servo/components/style/gecko/media_features.rs  | 17 ++++++++---------
 .../css/mediaqueries/prefers-contrast.html      | 12 ++++++++----
 5 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/layout/reftests/high-contrast/prefers-contrast-002.html b/layout/reftests/high-contrast/prefers-contrast-002.html
index bd1984db5424..56bd8329bb8b 100644
--- a/layout/reftests/high-contrast/prefers-contrast-002.html
+++ b/layout/reftests/high-contrast/prefers-contrast-002.html
@@ -9,7 +9,7 @@
         width: 100px;
         height: 100px;
     }
-    @media (prefers-contrast: high) {
+    @media (prefers-contrast: more) {
         div {
             outline: 2px solid #000000;
         }
diff --git a/layout/style/nsMediaFeatures.cpp b/layout/style/nsMediaFeatures.cpp
index 58f9ac561fd8..8691993dbc39 100644
--- a/layout/style/nsMediaFeatures.cpp
+++ b/layout/style/nsMediaFeatures.cpp
@@ -281,7 +281,7 @@ StyleContrastPref Gecko_MediaFeatures_PrefersContrast(
   // https://github.com/w3c/csswg-drafts/issues/3856#issuecomment-642313572
   // https://github.com/w3c/csswg-drafts/issues/2943
   if (!!LookAndFeel::GetInt(LookAndFeel::IntID::UseAccessibilityTheme, 0)) {
-    return StyleContrastPref::High;
+    return StyleContrastPref::More;
   }
   return StyleContrastPref::NoPreference;
 }
diff --git a/layout/style/test/chrome/test_chrome_only_media_queries.html b/layout/style/test/chrome/test_chrome_only_media_queries.html
index 02861447a399..de7e41dcfa33 100644
--- a/layout/style/test/chrome/test_chrome_only_media_queries.html
+++ b/layout/style/test/chrome/test_chrome_only_media_queries.html
@@ -74,9 +74,9 @@
 expectParseable("(-moz-os-version: windows-win10)");
 expectNonParseable("(-moz-os-version: )");
 
-expectParseable("(prefers-contrast: low)")
+expectParseable("(prefers-contrast: more)")
 expectParseable("(prefers-contrast: forced)")
 expectParseable("(prefers-contrast: no-preference)")
-expectParseable("(prefers-contrast: high)");
+expectParseable("(prefers-contrast: less)");
 expectParseable("(prefers-contrast)")
 </script>
diff --git a/servo/components/style/gecko/media_features.rs b/servo/components/style/gecko/media_features.rs
index 0a86980167c2..ef08cafabe04 100644
--- a/servo/components/style/gecko/media_features.rs
+++ b/servo/components/style/gecko/media_features.rs
@@ -313,8 +313,8 @@ fn eval_prefers_reduced_motion(device: &Device, query_value: Option<PrefersReduc
 #[repr(u8)]
 #[allow(missing_docs)]
 enum PrefersContrast {
-    High,
-    Low,
+    More,
+    Less,
     NoPreference,
     Forced,
 }
@@ -326,12 +326,11 @@ enum PrefersContrast {
 #[derive(Clone, Copy, Debug, FromPrimitive, PartialEq)]
 #[repr(u8)]
 pub enum ContrastPref {
-    /// High contrast is prefered. Corresponds to an accessibility theme
+    /// More contrast is prefered. Corresponds to an accessibility theme
     /// being enabled or firefox forcing high contrast colors.
-    High,
-    /// Low contrast is prefered. Corresponds to the
-    /// browser.display.prefers_low_contrast pref being true.
-    Low,
+    More,
+    /// Low contrast is prefered.
+    Less,
     /// The default value if neither high or low contrast is enabled.
     NoPreference,
 }
@@ -344,8 +343,8 @@ fn eval_prefers_contrast(device: &Device, query_value: Option<PrefersContrast>)
     if let Some(query_value) = query_value {
         match query_value {
             PrefersContrast::Forced => forced_colors,
-            PrefersContrast::High => contrast_pref == ContrastPref::High,
-            PrefersContrast::Low => contrast_pref == ContrastPref::Low,
+            PrefersContrast::More => contrast_pref == ContrastPref::More,
+            PrefersContrast::Less => contrast_pref == ContrastPref::Less,
             PrefersContrast::NoPreference => contrast_pref == ContrastPref::NoPreference,
         }
     } else {
diff --git a/testing/web-platform/tests/css/mediaqueries/prefers-contrast.html b/testing/web-platform/tests/css/mediaqueries/prefers-contrast.html
index 617e0b97256d..fe0d2f057c31 100644
--- a/testing/web-platform/tests/css/mediaqueries/prefers-contrast.html
+++ b/testing/web-platform/tests/css/mediaqueries/prefers-contrast.html
@@ -7,8 +7,8 @@
 <script>
 query_should_be_css_parseable("(prefers-contrast)");
 query_should_be_css_parseable("(prefers-contrast: no-preference)");
-query_should_be_css_parseable("(prefers-contrast: high)");
-query_should_be_css_parseable("(prefers-contrast: low)");
+query_should_be_css_parseable("(prefers-contrast: more)");
+query_should_be_css_parseable("(prefers-contrast: less)");
 query_should_be_css_parseable("(prefers-contrast: forced)");
 
 query_should_not_be_css_parseable("(prefers-contrast: increase)");
@@ -18,11 +18,13 @@
 query_should_not_be_css_parseable("(prefers-contrast > increase)");
 query_should_not_be_css_parseable("(prefers-increased-contrast)");
 query_should_not_be_css_parseable("(prefers-decreased-contrast)");
+query_should_not_be_css_parseable("(prefers-contrast: high)");
+query_should_not_be_css_parseable("(prefers-contrast: low)");
 
 query_should_be_js_parseable("(prefers-contrast)");
 query_should_be_js_parseable("(prefers-contrast: no-preference)");
-query_should_be_js_parseable("(prefers-contrast: high)");
-query_should_be_js_parseable("(prefers-contrast: low)");
+query_should_be_js_parseable("(prefers-contrast: more)");
+query_should_be_js_parseable("(prefers-contrast: less)");
 query_should_be_js_parseable("(prefers-contrast: forced)");
 
 query_should_not_be_js_parseable("(prefers-contrast: increase)");
@@ -32,6 +34,8 @@
 query_should_not_be_js_parseable("(prefers-contrast > increase)");
 query_should_not_be_js_parseable("(prefers-increased-contrast)");
 query_should_not_be_js_parseable("(prefers-decreased-contrast)");
+query_should_not_be_js_parseable("(prefers-contrast: high)");
+query_should_not_be_js_parseable("(prefers-contrast: low)");
 
 test(() => {
   // no-preference is the default and all other values evaluate to