Rename usesOverlayScrollbars of settings to mockScrollbarsUseOverlay

Source/core/page/Settings.h

Index: Source/core/page/Settings.h
diff --git a/Source/core/page/Settings.h b/Source/core/page/Settings.h
index 9fe3bfa6d61666771c3ba92e53a21f07be7ad60e..7f56bb45fd7d4b9d2e85400db6c0b5a42ffe0789 100644
--- a/Source/core/page/Settings.h
+++ b/Source/core/page/Settings.h
@@ -142,8 +142,8 @@ public:
     static void setMockScrollbarsEnabled(bool flag);
     static bool mockScrollbarsEnabled();
 
-    static void setUsesOverlayScrollbars(bool flag);
-    static bool usesOverlayScrollbars();
+    static void setMockScrollbarsUseOverlay(bool flag);
+    static bool mockScrollbarsUseOverlay();
 
     void setTouchEventEmulationEnabled(bool enabled) { m_touchEventEmulationEnabled = enabled; }
     bool isTouchEventEmulationEnabled() const { return m_touchEventEmulationEnabled; }
@@ -202,7 +202,7 @@ private:
     void imageLoadingSettingsTimerFired(Timer<Settings>*);
 
     static bool gMockScrollbarsEnabled;
-    static bool gUsesOverlayScrollbars;
+    static bool gMockScrollbarsUseOverlay;
 };
 
 } // namespace WebCore