Initial skeleton of high-contrast mode.

third_party/WebKit/Source/platform/graphics/HighContrast.h

Index: third_party/WebKit/Source/platform/graphics/HighContrast.h
diff --git a/third_party/WebKit/Source/platform/graphics/HighContrast.h b/third_party/WebKit/Source/platform/graphics/HighContrast.h
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+++ b/third_party/WebKit/Source/platform/graphics/HighContrast.h
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+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef HighContrast_h
+#define HighContrast_h
+
+namespace blink {
+
+enum class HighContrastMode {
+  // Default, drawing is unfiltered.
+  kOff,
+  // For testing only, does a simple 8-bit invert of every RGB pixel component.
+  kSimpleInvertForTesting,
+  kInvertBrightness,
+  kInvertLightness,
+};
+
+struct HighContrastSettings {
+  HighContrastMode mode;
+  bool grayscale;
+  float contrast;  // Valid range from -1.0 to 1.0
+};
+
+}  // namespace blink
+
+#endif  // HighContrast_h