Aura overlay scrollbars adjust color for dark backgrounds

third_party/WebKit/public/platform/WebThemeEngine.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 15 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef WebThemeEngine_h
 #define WebThemeEngine_h
 
 #include "WebCanvas.h"
 #include "WebColor.h"
+#include "WebScrollbarOverlayColorTheme.h"
 #include "WebSize.h"
 
 namespace blink {
 
 struct WebRect;
 
 class WebThemeEngine {
  public:
   // The current state of the associated Part.
   enum State {
@@ skipping 84 matching lines @@
 
   // Extra parameters for PartProgressBar
   struct ProgressBarExtraParams {
     bool determinate;
     int valueRectX;
     int valueRectY;
     int valueRectWidth;
     int valueRectHeight;
   };
 
+  // Extra parameters for Scrollbar, now only for overlay-scrollbar

[bokan, 2016/10/21 20:11:38]

Nit: Extra parameters for scrollbar thumb. Used only for overlay scrollbars.

+  struct ScrollbarThumbExtraParams {
+    WebScrollbarOverlayColorTheme scrollbarTheme;
+  };
+
   union ExtraParams {
     ScrollbarTrackExtraParams scrollbarTrack;
     ButtonExtraParams button;
     TextFieldExtraParams textField;
     MenuListExtraParams menuList;
     SliderExtraParams slider;
     InnerSpinButtonExtraParams innerSpin;
     ProgressBarExtraParams progressBar;
+    ScrollbarThumbExtraParams scrollbarThumb;
   };
 
   // Gets the size of the given theme part. For variable sized items
   // like vertical scrollbar thumbs, the width will be the required width of
   // the track while the height will be the minimum height.
   virtual WebSize getSize(Part) { return WebSize(); }
 
   struct ScrollbarStyle {
     int thumbThickness;
     int scrollbarMargin;
     WebColor color;
   };
 
   // Gets the overlay scrollbar style. Used for mobile theme.
   virtual void getOverlayScrollbarStyle(ScrollbarStyle*) {}
 
   // Paint the given the given theme part.
   virtual void paint(WebCanvas*,
                      Part,
                      State,
                      const WebRect&,
                      const ExtraParams*) {}
 };
 
 }  // namespace blink
 
 #endif