Initial skeleton of high-contrast mode.

third_party/WebKit/Source/core/frame/Settings.json5

Index: third_party/WebKit/Source/core/frame/Settings.json5
diff --git a/third_party/WebKit/Source/core/frame/Settings.json5 b/third_party/WebKit/Source/core/frame/Settings.json5
index a45cdb299e2455bb8b8b4b9dfb3f0d94d09f3ce8..798ae0f0dc91bb2b33605b092478f0d49588d288 100644
--- a/third_party/WebKit/Source/core/frame/Settings.json5
+++ b/third_party/WebKit/Source/core/frame/Settings.json5
@@ -931,5 +931,23 @@
       type: "AutoplayPolicy::Type",
       initial: "AutoplayPolicy::Type::kNoUserGestureRequired",
     },
+
+    //
+    // High contrast mode
+    //
+    {
+      name: "highContrastMode",
+      initial: "HighContrastMode::kOff",
+      type: "HighContrastMode",
+    },
+    {
+      name: "highContrastGrayscale",
+      initial: false,
+    },
+    {
+      name: "highContrastContrast",
+      initial: 0,
+      type: "double",
+    }
   ],
 }