Fix overlay scroll bar color on elements with dark background

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

Index: third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp b/third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp
index d89e693f05becf7c0b7bba1402c66045f8182314..4633bc4af8467013c9e5c4e428bab270a42f4ce9 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp
@@ -4,6 +4,7 @@
 
 #include "platform/scroll/ScrollableArea.h"
 
+#include "platform/graphics/Color.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/scroll/ScrollbarTheme.h"
 #include "platform/scroll/ScrollbarThemeMock.h"
@@ -280,4 +281,15 @@ TEST_F(ScrollableAreaTest, InvalidatesCompositedScrollbarsIfPartsNeedRepaint)
     Heap::collectAllGarbage();
 }
 
+TEST_F(ScrollableAreaTest, RecalculatesScrollbarOverlayIfBackgroundChanges)
+{
+    OwnPtrWillBeRawPtr<MockScrollableArea> scrollableArea = MockScrollableArea::create(IntPoint(0, 100));
+
+    EXPECT_EQ(ScrollbarOverlayStyleDefault, scrollableArea->getScrollbarOverlayStyle());
+    scrollableArea->recalculateScrollbarOverlayStyle(Color(34, 85, 51));
+    EXPECT_EQ(ScrollbarOverlayStyleLight, scrollableArea->getScrollbarOverlayStyle());
+    scrollableArea->recalculateScrollbarOverlayStyle(Color(236, 143, 185));
+    EXPECT_EQ(ScrollbarOverlayStyleDefault, scrollableArea->getScrollbarOverlayStyle());
+}
+
 } // namespace blink