Mac: Add rails for scrolling.

content/browser/renderer_host/input/mouse_wheel_rails_filter_unittest_mac.cc

+// Copyright 2015 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.
+
+#include "content/browser/renderer_host/input/mouse_wheel_rails_filter_mac.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using blink::WebInputEvent;
+using blink::WebMouseWheelEvent;
+
+namespace content {
+namespace {
+
+WebMouseWheelEvent MakeEvent(WebMouseWheelEvent::Phase phase,
+                             float delta_x,
+                             float delta_y) {
+  WebMouseWheelEvent event;
+  event.phase = phase;
+  event.deltaX = delta_x;
+  event.deltaY = delta_y;
+  return event;
+}
+
+TEST(MouseWheelRailsFilterMacTest, Functionality) {
+  WebInputEvent::RailsMode mode;
+  MouseWheelRailsFilterMac filter;
+
+  // Start with a mostly-horizontal event and see that it is locked
+  // horizontally and continues to be locked.
+  mode =
+      filter.UpdateRailsMode(MakeEvent(WebMouseWheelEvent::PhaseBegan, 2, 1));
+  EXPECT_EQ(mode, WebInputEvent::RailsModeHorizontal);
+  mode = filter.UpdateRailsMode(
+      MakeEvent(WebMouseWheelEvent::PhaseChanged, 2, 2));
+  EXPECT_EQ(mode, WebInputEvent::RailsModeHorizontal);
+  mode = filter.UpdateRailsMode(
+      MakeEvent(WebMouseWheelEvent::PhaseChanged, 10, -4));
+  EXPECT_EQ(mode, WebInputEvent::RailsModeHorizontal);
+
+  // Change from horizontal to vertical and back.
+  mode =
+      filter.UpdateRailsMode(MakeEvent(WebMouseWheelEvent::PhaseBegan, 4, 1));
+  EXPECT_EQ(mode, WebInputEvent::RailsModeHorizontal);
+  mode = filter.UpdateRailsMode(
+      MakeEvent(WebMouseWheelEvent::PhaseChanged, 3, 4));
+  EXPECT_EQ(mode, WebInputEvent::RailsModeHorizontal);
+  mode = filter.UpdateRailsMode(
+      MakeEvent(WebMouseWheelEvent::PhaseChanged, 1, 4));
+  EXPECT_EQ(mode, WebInputEvent::RailsModeVertical);
+  mode = filter.UpdateRailsMode(
+      MakeEvent(WebMouseWheelEvent::PhaseChanged, 10, 0));
+  EXPECT_EQ(mode, WebInputEvent::RailsModeHorizontal);
+
+  // Make sure zeroes don't break things.
+  mode = filter.UpdateRailsMode(
+      MakeEvent(WebMouseWheelEvent::PhaseChanged, 0, 0));
+  EXPECT_EQ(mode, WebInputEvent::RailsModeFree);
+  mode =
+      filter.UpdateRailsMode(MakeEvent(WebMouseWheelEvent::PhaseBegan, 0, 0));
+  EXPECT_EQ(mode, WebInputEvent::RailsModeFree);
+}
+
+}  // namespace
+}  // namespace content