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

third_party/WebKit/Source/platform/scroll/ScrollbarTestSuite.h

Index: third_party/WebKit/Source/platform/scroll/ScrollbarTestSuite.h
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollbarTestSuite.h b/third_party/WebKit/Source/platform/scroll/ScrollbarTestSuite.h
new file mode 100644
index 0000000000000000000000000000000000000000..a0551daf066d52202c4f3b69dc25e1e0a12e284a
--- /dev/null
+++ b/third_party/WebKit/Source/platform/scroll/ScrollbarTestSuite.h
@@ -0,0 +1,106 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.

[jbroman, 2016/05/13 17:35:49]

This file is not listed in the build files; please add it (probably to
platform_test_support_files in blink_platform.gypi).

[Bret, 2016/05/13 22:11:00]

Done. The other test support files like ScrollbarThemeMock.h are under
platform_files, but that kinda seems wrong so I did what you said.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ScrollbarTestSuite_h
+#define ScrollbarTestSuite_h
+
+#include "platform/heap/GarbageCollected.h"
+#include "platform/scroll/ScrollableArea.h"
+#include "platform/scroll/Scrollbar.h"
+#include "platform/scroll/ScrollbarThemeMock.h"
+#include "platform/testing/TestingPlatformSupport.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace blink {
+
+class MockScrollableArea : public GarbageCollectedFinalized<MockScrollableArea>, public ScrollableArea {
+    USING_GARBAGE_COLLECTED_MIXIN(MockScrollableArea);
+
+public:
+    static MockScrollableArea* create()
+    {
+        return new MockScrollableArea();
+    }
+
+    static MockScrollableArea* create(const IntPoint& maximumScrollPosition)
+    {
+        MockScrollableArea* mock = create();
+        mock->setMaximumScrollPosition(maximumScrollPosition);
+        return mock;
+    }
+
+    MOCK_CONST_METHOD0(visualRectForScrollbarParts, LayoutRect());
+    MOCK_CONST_METHOD0(isActive, bool());
+    MOCK_CONST_METHOD1(scrollSize, int(ScrollbarOrientation));
+    MOCK_CONST_METHOD0(isScrollCornerVisible, bool());
+    MOCK_CONST_METHOD0(scrollCornerRect, IntRect());
+    MOCK_CONST_METHOD0(horizontalScrollbar, Scrollbar*());
+    MOCK_CONST_METHOD0(verticalScrollbar, Scrollbar*());
+    MOCK_CONST_METHOD0(enclosingScrollableArea, ScrollableArea*());
+    MOCK_CONST_METHOD1(visibleContentRect, IntRect(IncludeScrollbarsInRect));
+    MOCK_CONST_METHOD0(contentsSize, IntSize());
+    MOCK_CONST_METHOD0(scrollableAreaBoundingBox, IntRect());
+    MOCK_CONST_METHOD0(layerForHorizontalScrollbar, GraphicsLayer*());
+    MOCK_CONST_METHOD0(layerForVerticalScrollbar, GraphicsLayer*());
+
+    bool userInputScrollable(ScrollbarOrientation) const override { return true; }
+    bool scrollbarsCanBeActive() const override { return true; }
+    bool shouldPlaceVerticalScrollbarOnLeft() const override { return false; }
+    void setScrollOffset(const DoublePoint& offset, ScrollType) override { m_scrollPosition = flooredIntPoint(offset).shrunkTo(m_maximumScrollPosition); }
+    IntPoint scrollPosition() const override { return m_scrollPosition; }
+    IntPoint minimumScrollPosition() const override { return IntPoint(); }
+    IntPoint maximumScrollPosition() const override { return m_maximumScrollPosition; }
+    int visibleHeight() const override { return 768; }
+    int visibleWidth() const override { return 1024; }
+    bool scrollAnimatorEnabled() const override { return false; }
+    int pageStep(ScrollbarOrientation) const override { return 0; }
+    void scrollControlWasSetNeedsPaintInvalidation() {}
+
+    using ScrollableArea::horizontalScrollbarNeedsPaintInvalidation;
+    using ScrollableArea::verticalScrollbarNeedsPaintInvalidation;
+    using ScrollableArea::clearNeedsPaintInvalidationForScrollControls;
+
+    DEFINE_INLINE_VIRTUAL_TRACE()
+    {
+        ScrollableArea::trace(visitor);
+    }
+
+private:
+    void setMaximumScrollPosition(const IntPoint& maximumScrollPosition)
+    {
+        m_maximumScrollPosition = maximumScrollPosition;
+    }
+
+    explicit MockScrollableArea()
+        : m_maximumScrollPosition(IntPoint(0, 100))
+    {
+    }
+
+    IntPoint m_scrollPosition;
+    IntPoint m_maximumScrollPosition;
+};
+
+class ScrollbarTestSuite : public testing::Test {
+public:
+    ScrollbarTestSuite() {}
+
+    void SetUp() override
+    {
+        TestingPlatformSupport::Config config;
+        config.compositorSupport = Platform::current()->compositorSupport();
+        m_fakePlatform = adoptPtr(new TestingPlatformSupportWithMockScheduler(config));
+    }
+
+    void TearDown() override
+    {
+        m_fakePlatform = nullptr;
+    }
+
+private:
+    OwnPtr<TestingPlatformSupportWithMockScheduler> m_fakePlatform;
+};
+
+} // namespace blink
+
+#endif