1 files changed, 43 insertions, 0 deletions
diff --git a/chromium/cc/input/scroll_utils.h b/chromium/cc/input/scroll_utils.h
new file mode 100644
index 00000000000..34fb3be7773
--- /dev/null
+++ b/chromium/cc/input/scroll_utils.h
@@ -0,0 +1,43 @@
+// Copyright 2020 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 CC_INPUT_SCROLL_UTILS_H_
+#define CC_INPUT_SCROLL_UTILS_H_
+
+#include "cc/cc_export.h"
+
+namespace gfx {
+class Vector2dF;
+class SizeF;
+}  // namespace gfx
+
+namespace cc {
+
+static constexpr int kPixelsPerLineStep = 40;
+static constexpr float kMinFractionToStepWhenPaging = 0.875f;
+
+// Each directional scroll for percentage-based units should scroll 1/8th of
+// the scrollable area.
+static constexpr float kPercentDeltaForDirectionalScroll = 0.125f;
+
+// Scroll deltas are lower-bounded by 16 physical pixels in percent-based
+// scrolls.
+static constexpr float kMinPixelDeltaForPercentBasedScroll = 16;
+
+// Class for scroll helper methods in cc and blink.
+class CC_EXPORT ScrollUtils {
+ public:
+  // Transforms a |scroll_delta| in percent units to pixel units based in its
+  // |scroller_size|. Clamps it by 16 pixels to avoid too small deltas for tiny
+  // scrollers and 12.5% of |viewport_size| to avoid too large deltas.
+  // Inputs and output muest be in physical pixels.
+  static gfx::Vector2dF ResolveScrollPercentageToPixels(
+      const gfx::Vector2dF& scroll_delta,
+      const gfx::SizeF& scroller_size,
+      const gfx::SizeF& viewport_size);
+};
+
+}  // namespace cc
+
+#endif  // CC_INPUT_SCROLL_UTILS_H_