Mac: Don't repaint scrollbars every frame

third_party/WebKit/Source/platform/exported/WebScrollbarThemePainter.cpp

 /*
  * Copyright (C) 2012 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 50 matching lines @@
     pictureBuilder.endRecording()->playback(canvas);
 }
 
 void WebScrollbarThemePainter::paintTrackBackground(WebCanvas* canvas, const WebRect& rect)
 {
     IntRect intRect(rect);
     SkPictureBuilder pictureBuilder(intRect);
     pictureBuilder.context().setDeviceScaleFactor(m_deviceScaleFactor);
     m_theme->paintTrackBackground(&pictureBuilder.context(), m_scrollbar.get(), intRect);
     pictureBuilder.endRecording()->playback(canvas);
+    if (!m_theme->shouldRepaintAllPartsOnInvalidation())
+        m_scrollbar->setTrackNeedsRepaint(false);
 }
 
 void WebScrollbarThemePainter::paintBackTrackPart(WebCanvas* canvas, const WebRect& rect)
 {
     IntRect intRect(rect);
     SkPictureBuilder pictureBuilder(intRect);
     pictureBuilder.context().setDeviceScaleFactor(m_deviceScaleFactor);
     m_theme->paintTrackPiece(&pictureBuilder.context(), m_scrollbar.get(), intRect, BackTrackPart);
     pictureBuilder.endRecording()->playback(canvas);
 }
@@ skipping 52 matching lines @@
     pictureBuilder.endRecording()->playback(canvas);
 }
 
 void WebScrollbarThemePainter::paintThumb(WebCanvas* canvas, const WebRect& rect)
 {
     IntRect intRect(rect);
     SkPictureBuilder pictureBuilder(intRect);
     pictureBuilder.context().setDeviceScaleFactor(m_deviceScaleFactor);
     m_theme->paintThumb(&pictureBuilder.context(), m_scrollbar.get(), intRect);
     pictureBuilder.endRecording()->playback(canvas);
+    if (!m_theme->shouldRepaintAllPartsOnInvalidation())
+        m_scrollbar->setThumbNeedsRepaint(false);
 }
 
 WebScrollbarThemePainter::WebScrollbarThemePainter(ScrollbarTheme* theme, Scrollbar* scrollbar, float deviceScaleFactor)
     : m_theme(theme)
     , m_scrollbar(scrollbar)
     , m_deviceScaleFactor(deviceScaleFactor)
 {
 }
 
+float WebScrollbarThemePainter::thumbOpacity() const
+{
+    return m_theme->thumbOpacity(m_scrollbar.get());
+}
+
+bool WebScrollbarThemePainter::trackNeedsRepaint() const
+{
+    return m_scrollbar->trackNeedsRepaint();
+}
+
+bool WebScrollbarThemePainter::thumbNeedsRepaint() const
+{
+    return m_scrollbar->thumbNeedsRepaint();
+}
+
 } // namespace blink