Aura overlay scrollbars shouldn't invalidate thumb on scroll or enabled state.

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
index a4789a58fc390fd3036d9b87bfcd061776fab193..6bb469fd2122046298c088d22d70046e044c9eb7 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollbarTestSuite.h
+++ b/third_party/WebKit/Source/platform/scroll/ScrollbarTestSuite.h
@@ -34,14 +34,14 @@ class MockScrollableArea : public GarbageCollectedFinalized<MockScrollableArea>,
   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*());
+  MOCK_CONST_METHOD0(horizontalScrollbar, Scrollbar*());
+  MOCK_CONST_METHOD0(verticalScrollbar, Scrollbar*());
 
   bool userInputScrollable(ScrollbarOrientation) const override { return true; }
   bool scrollbarsCanBeActive() const override { return true; }
@@ -68,13 +68,16 @@ class MockScrollableArea : public GarbageCollectedFinalized<MockScrollableArea>,
 
   DEFINE_INLINE_VIRTUAL_TRACE() { ScrollableArea::trace(visitor); }
 
+ protected:
+  explicit MockScrollableArea() : m_maximumScrollOffset(ScrollOffset(0, 100)) {}
+  explicit MockScrollableArea(const ScrollOffset& offset)
+      : m_maximumScrollOffset(offset) {}
+
  private:
   void setMaximumScrollOffset(const ScrollOffset& maximumScrollOffset) {
     m_maximumScrollOffset = maximumScrollOffset;
   }
 
-  explicit MockScrollableArea() : m_maximumScrollOffset(ScrollOffset(0, 100)) {}
-
   ScrollOffset m_scrollOffset;
   ScrollOffset m_maximumScrollOffset;
 };