Deal gracefully with null {GraphicsContext,SkPictureBuilder}.endRecording() results.

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 29 matching lines @@
     m_theme = painter.m_theme;
     m_scrollbar = painter.m_scrollbar;
     m_deviceScaleFactor = painter.m_deviceScaleFactor;
 }
 
 void WebScrollbarThemePainter::reset()
 {
     m_scrollbar = nullptr;
 }
 
+static void playbackIfNeeded(SkPictureBuilder* builder, WebCanvas* canvas)

[chrishtr, 2016/03/29 22:42:23]

the "IfNeeded" suffix is now deprecated :)

[wkorman, 2016/03/29 22:52:02]

Removed suffix.

+{
+    RefPtr<const SkPicture> recording = builder->endRecording();
+    if (recording)
+        recording->playback(canvas);
+}
+
 void WebScrollbarThemePainter::paintScrollbarBackground(WebCanvas* canvas, const WebRect& rect)
 {
     SkRect clip = SkRect::MakeXYWH(rect.x, rect.y, rect.width, rect.height);
     canvas->clipRect(clip);
 
     IntRect intRect(rect);
     SkPictureBuilder pictureBuilder(intRect);
     pictureBuilder.context().setDeviceScaleFactor(m_deviceScaleFactor);
     m_theme->paintScrollbarBackground(pictureBuilder.context(), *m_scrollbar);
-    pictureBuilder.endRecording()->playback(canvas);
+    playbackIfNeeded(&pictureBuilder, 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, intRect);
-    pictureBuilder.endRecording()->playback(canvas);
+    playbackIfNeeded(&pictureBuilder, canvas);
     if (!m_theme->shouldRepaintAllPartsOnInvalidation())
         m_scrollbar->clearTrackNeedsRepaint();
 }
 
 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, intRect, BackTrackPart);
-    pictureBuilder.endRecording()->playback(canvas);
+    playbackIfNeeded(&pictureBuilder, canvas);
 }
 
 void WebScrollbarThemePainter::paintForwardTrackPart(WebCanvas* canvas, const WebRect& rect)
 {
     IntRect intRect(rect);
     SkPictureBuilder pictureBuilder(intRect);
     pictureBuilder.context().setDeviceScaleFactor(m_deviceScaleFactor);
     m_theme->paintTrackPiece(pictureBuilder.context(), *m_scrollbar, intRect, ForwardTrackPart);
-    pictureBuilder.endRecording()->playback(canvas);
+    playbackIfNeeded(&pictureBuilder, canvas);
 }
 
 void WebScrollbarThemePainter::paintBackButtonStart(WebCanvas* canvas, const WebRect& rect)
 {
     IntRect intRect(rect);
     SkPictureBuilder pictureBuilder(intRect);
     pictureBuilder.context().setDeviceScaleFactor(m_deviceScaleFactor);
     m_theme->paintButton(pictureBuilder.context(), *m_scrollbar, intRect, BackButtonStartPart);
-    pictureBuilder.endRecording()->playback(canvas);
+    playbackIfNeeded(&pictureBuilder, canvas);
 }
 
 void WebScrollbarThemePainter::paintBackButtonEnd(WebCanvas* canvas, const WebRect& rect)
 {
     IntRect intRect(rect);
     SkPictureBuilder pictureBuilder(intRect);
     pictureBuilder.context().setDeviceScaleFactor(m_deviceScaleFactor);
     m_theme->paintButton(pictureBuilder.context(), *m_scrollbar, intRect, BackButtonEndPart);
-    pictureBuilder.endRecording()->playback(canvas);
+    playbackIfNeeded(&pictureBuilder, canvas);
 }
 
 void WebScrollbarThemePainter::paintForwardButtonStart(WebCanvas* canvas, const WebRect& rect)
 {
     IntRect intRect(rect);
     SkPictureBuilder pictureBuilder(intRect);
     pictureBuilder.context().setDeviceScaleFactor(m_deviceScaleFactor);
     m_theme->paintButton(pictureBuilder.context(), *m_scrollbar, intRect, ForwardButtonStartPart);
-    pictureBuilder.endRecording()->playback(canvas);
+    playbackIfNeeded(&pictureBuilder, canvas);
 }
 
 void WebScrollbarThemePainter::paintForwardButtonEnd(WebCanvas* canvas, const WebRect& rect)
 {
     IntRect intRect(rect);
     SkPictureBuilder pictureBuilder(intRect);
     pictureBuilder.context().setDeviceScaleFactor(m_deviceScaleFactor);
     m_theme->paintButton(pictureBuilder.context(), *m_scrollbar, intRect, ForwardButtonEndPart);
-    pictureBuilder.endRecording()->playback(canvas);
+    playbackIfNeeded(&pictureBuilder, canvas);
 }
 
 void WebScrollbarThemePainter::paintTickmarks(WebCanvas* canvas, const WebRect& rect)
 {
     IntRect intRect(rect);
     SkPictureBuilder pictureBuilder(intRect);
     pictureBuilder.context().setDeviceScaleFactor(m_deviceScaleFactor);
     m_theme->paintTickmarks(pictureBuilder.context(), *m_scrollbar, intRect);
-    pictureBuilder.endRecording()->playback(canvas);
+    playbackIfNeeded(&pictureBuilder, 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, intRect);
-    pictureBuilder.endRecording()->playback(canvas);
+    playbackIfNeeded(&pictureBuilder, canvas);
     if (!m_theme->shouldRepaintAllPartsOnInvalidation())
         m_scrollbar->clearThumbNeedsRepaint();
 }
 
 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);
 }
 
 bool WebScrollbarThemePainter::trackNeedsRepaint() const
 {
     return m_scrollbar->trackNeedsRepaint();
 }
 
 bool WebScrollbarThemePainter::thumbNeedsRepaint() const
 {
     return m_scrollbar->thumbNeedsRepaint();
 }
 
 } // namespace blink