Fix scrollbar buttons on ChromeOS.

third_party/WebKit/Source/platform/scroll/ScrollbarThemeAuraTest.cpp

Index: third_party/WebKit/Source/platform/scroll/ScrollbarThemeAuraTest.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeAuraTest.cpp b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeAuraTest.cpp
index 110ca2f089883c4dea2818522ca7350d0aa72097..a80b75a2f8851022c220dc9d26ddd1df27b9bd0b 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeAuraTest.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeAuraTest.cpp
@@ -10,6 +10,31 @@ namespace blink {
 
 using testing::Return;
 
+namespace {
+
+class ScrollbarThemeAuraButtonOverride final : public ScrollbarThemeAura {
+public:
+    ScrollbarThemeAuraButtonOverride()
+        : m_hasScrollbarButtons(true)
+    {
+    }
+
+    void setHasScrollbarButtons(bool value)
+    {
+        m_hasScrollbarButtons = value;
+    }
+
+    bool hasScrollbarButtons(ScrollbarOrientation unused) const override
+    {
+        return m_hasScrollbarButtons;
+    }
+
+private:
+    bool m_hasScrollbarButtons;
+};
+
+} // namespace
+
 class ScrollbarThemeAuraTest : public ScrollbarTestSuite {
 };
 
@@ -19,7 +44,7 @@ TEST_F(ScrollbarThemeAuraTest, ButtonSizeHorizontal)
     ScrollbarThemeMock mockTheme;
     Scrollbar* scrollbar = Scrollbar::createForTesting(
         mockScrollableArea, HorizontalScrollbar, RegularScrollbar, &mockTheme);
-    ScrollbarThemeAura theme;
+    ScrollbarThemeAuraButtonOverride theme;
 
     IntRect scrollbarSizeNormalDimensions(11, 22, 444, 66);
     scrollbar->setFrameRect(scrollbarSizeNormalDimensions);
@@ -42,7 +67,7 @@ TEST_F(ScrollbarThemeAuraTest, ButtonSizeVertical)
     ScrollbarThemeMock mockTheme;
     Scrollbar* scrollbar = Scrollbar::createForTesting(
         mockScrollableArea, VerticalScrollbar, RegularScrollbar, &mockTheme);
-    ScrollbarThemeAura theme;
+    ScrollbarThemeAuraButtonOverride theme;
 
     IntRect scrollbarSizeNormalDimensions(11, 22, 44, 666);
     scrollbar->setFrameRect(scrollbarSizeNormalDimensions);
@@ -59,4 +84,21 @@ TEST_F(ScrollbarThemeAuraTest, ButtonSizeVertical)
     ThreadHeap::collectAllGarbage();
 }
 
+TEST_F(ScrollbarThemeAuraTest, NoButtonsReturnsSize0)
+{
+    MockScrollableArea* mockScrollableArea = MockScrollableArea::create();
+    ScrollbarThemeMock mockTheme;
+    Scrollbar* scrollbar = Scrollbar::createForTesting(
+        mockScrollableArea, VerticalScrollbar, RegularScrollbar, &mockTheme);
+    ScrollbarThemeAuraButtonOverride theme;
+    theme.setHasScrollbarButtons(false);
+
+    scrollbar->setFrameRect(IntRect(1, 2, 3, 4));
+    IntSize size = theme.buttonSize(*scrollbar);
+    EXPECT_EQ(0, size.width());
+    EXPECT_EQ(0, size.height());
+
+    ThreadHeap::collectAllGarbage();
+}
+
 } // namespace blink