Fix scrollbar buttons at hidpi when enable-use-zoom-for-dsf is on.

ui/native_theme/native_theme_aura_unittest.cc

+// Copyright 2016 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 "ui/native_theme/native_theme_aura.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/skia/include/core/SkPath.h"
+#include "ui/gfx/geometry/rect.h"
+#include "ui/native_theme/native_theme.h"
+
+namespace ui {
+namespace {
+void VerifyPoint(SkPoint a, SkPoint b) {
+  EXPECT_EQ(a.x(), b.x());
+  EXPECT_EQ(a.y(), b.y());
+}
+
+void VerifyTriangle(SkPath actualPath, SkPoint p0, SkPoint p1, SkPoint p2) {
+  EXPECT_EQ(3, actualPath.countPoints());
+  VerifyPoint(p0, actualPath.getPoint(0));
+  VerifyPoint(p1, actualPath.getPoint(1));
+  VerifyPoint(p2, actualPath.getPoint(2));
+}
+}
+
+TEST(NativeThemeAuraTest, VerticalArrows) {
+  NativeThemeAura* theme = NativeThemeAura::instance();
+  SkPath path;
+
+  // Up arrow, sized for 1x.
+  path = theme->PathForArrow(gfx::Rect(100, 200, 17, 17),
+                             NativeTheme::kScrollbarUpArrow);
+  VerifyTriangle(path, SkPoint::Make(105, 211), SkPoint::Make(112, 211),
+                 SkPoint::Make(108.5, 207));
+
+  // 1.25x, should be larger.
+  path = theme->PathForArrow(gfx::Rect(50, 70, 21, 21),
+                             NativeTheme::kScrollbarUpArrow);
+  VerifyTriangle(path, SkPoint::Make(56, 84), SkPoint::Make(65, 84),
+                 SkPoint::Make(60.5, 79));
+
+  // Down arrow is just a flipped up arrow.
+  path = theme->PathForArrow(gfx::Rect(20, 80, 17, 17),
+                             NativeTheme::kScrollbarDownArrow);
+  VerifyTriangle(path, SkPoint::Make(25, 86), SkPoint::Make(32, 86),
+                 SkPoint::Make(28.5, 90));
+}
+
+TEST(NativeThemeAuraTest, HorizontalArrows) {
+  NativeThemeAura* theme = NativeThemeAura::instance();
+  SkPath path;
+
+  // Right arrow, sized for 1x.
+  path = theme->PathForArrow(gfx::Rect(100, 200, 17, 17),
+                             NativeTheme::kScrollbarRightArrow);
+  VerifyTriangle(path, SkPoint::Make(107, 205), SkPoint::Make(107, 212),
+                 SkPoint::Make(111, 208.5));
+
+  // Button size for 1.25x, should be larger.
+  path = theme->PathForArrow(gfx::Rect(50, 70, 21, 21),
+                             NativeTheme::kScrollbarRightArrow);
+  VerifyTriangle(path, SkPoint::Make(58, 76), SkPoint::Make(58, 85),
+                 SkPoint::Make(63, 80.5));
+
+  // Left arrow is just a flipped right arrow.
+  path = theme->PathForArrow(gfx::Rect(20, 80, 17, 17),
+                             NativeTheme::kScrollbarLeftArrow);
+  VerifyTriangle(path, SkPoint::Make(30, 85), SkPoint::Make(30, 92),
+                 SkPoint::Make(26, 88.5));
+}
+
+}  // namespace ui