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 7cac80b9b7fc1e797a51ad45ec564bee1cc00b09..86fd8a726d112f2d6eb735237d7591fe9d27936f 100644
--- a/third_party/WebKit/Source/core/frame/Settings.json5
+++ b/third_party/WebKit/Source/core/frame/Settings.json5
@@ -927,5 +927,23 @@
       name: "doNotUpdateSelectionOnMutatingSelectionRange",
       initial: false,
     },
+
+    //
+    // High contrast mode
+    //
+    {
+      name: "highContrastMode",
+      initial: "HighContrastMode::kOff",
+      type: "HighContrastMode",
+    },
+    {
+      name: "highContrastGrayscale",
+      initial: false,
+    },
+    {
+      name: "highContrastContrast",
+      initial: 0,
+      type: "double",
+    },
   ],
 }