Use correct ScrollbarTheme to paintScrollCorner

third_party/WebKit/Source/core/paint/FramePainter.cpp

Index: third_party/WebKit/Source/core/paint/FramePainter.cpp
diff --git a/third_party/WebKit/Source/core/paint/FramePainter.cpp b/third_party/WebKit/Source/core/paint/FramePainter.cpp
index 447f20c8db45d7eb37087094a254490b83302eac..a5c0b076f1f0910caeba18a8b17adc8a3fe54256 100644
--- a/third_party/WebKit/Source/core/paint/FramePainter.cpp
+++ b/third_party/WebKit/Source/core/paint/FramePainter.cpp
@@ -196,20 +196,28 @@ void FramePainter::paintContents(GraphicsContext& context,
 
 void FramePainter::paintScrollbars(GraphicsContext& context,
                                    const IntRect& rect) {
+  ScrollbarTheme* scrollbarTheme = nullptr;
   if (frameView().horizontalScrollbar() &&
-      !frameView().layerForHorizontalScrollbar())
+      !frameView().layerForHorizontalScrollbar()) {
     paintScrollbar(context, *frameView().horizontalScrollbar(), rect);
+    scrollbarTheme = &frameView().horizontalScrollbar()->theme();
+  }
   if (frameView().verticalScrollbar() &&
-      !frameView().layerForVerticalScrollbar())
+      !frameView().layerForVerticalScrollbar()) {
     paintScrollbar(context, *frameView().verticalScrollbar(), rect);
+    scrollbarTheme = &frameView().horizontalScrollbar()->theme();
+  }
 
   if (frameView().layerForScrollCorner())
     return;
 
-  paintScrollCorner(context, frameView().scrollCornerRect());
+  DCHECK(scrollbarTheme);
+  scrollbarTheme = scrollbarTheme ? scrollbarTheme : &ScrollbarTheme::theme();
+  paintScrollCorner(context, *scrollbarTheme, frameView().scrollCornerRect());
 }
 
 void FramePainter::paintScrollCorner(GraphicsContext& context,
+                                     ScrollbarTheme& theme,

[bokan, 2017/03/13 13:52:09]

Rather than passing the theme in, just computed it inside here, rather than
above and in PLC.

                                      const IntRect& cornerRect) {
   if (frameView().scrollCorner()) {
     bool needsBackground = frameView().frame().isMainFrame();
@@ -228,8 +236,7 @@ void FramePainter::paintScrollCorner(GraphicsContext& context,
     return;
   }
 
-  ScrollbarTheme::theme().paintScrollCorner(context, *frameView().layoutView(),
-                                            cornerRect);
+  theme.paintScrollCorner(context, *frameView().layoutView(), cornerRect);
 }
 
 void FramePainter::paintScrollbar(GraphicsContext& context,