Scale scrollbar in use-zoom-for-dsf mode

third_party/WebKit/Source/platform/scroll/ScrollbarThemeNonMacCommon.cpp

Index: third_party/WebKit/Source/platform/scroll/ScrollbarThemeNonMacCommon.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeNonMacCommon.cpp b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeNonMacCommon.cpp
index 837aece81427cb9623f5e964f16c865ec811550f..79018ed16d108ccd9db8ebd8e0529533a4618331 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeNonMacCommon.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeNonMacCommon.cpp
@@ -30,7 +30,6 @@
 #include "platform/graphics/GraphicsContextStateSaver.h"
 #include "platform/graphics/paint/DrawingRecorder.h"
 #include "platform/scroll/ScrollableArea.h"
-#include "platform/scroll/ScrollbarThemeClient.h"
 
 namespace blink {
 
@@ -73,11 +72,14 @@ IntRect ScrollbarThemeNonMacCommon::trackRect(const ScrollbarThemeClient& scroll
 {
     // The track occupies all space between the two buttons.
     IntSize bs = buttonSize(scrollbar);
-    int thickness = scrollbarThickness(scrollbar.controlSize());

[skobes, 2016/01/07 21:49:10]

The other caller of ScrollbarThemeClient::controlSize is
ScrollbarTheme::minimumThumbLength.  Does that need updating as well?

[oshima, 2016/01/09 00:58:39]

Other uses seems to be for custom scrollbars, which gets scaled properly when
zoomed.

+    int thickness;
     if (scrollbar.orientation() == HorizontalScrollbar) {
+        thickness = scrollbar.height();
         if (scrollbar.width() <= 2 * bs.width())
             return IntRect();
         return IntRect(scrollbar.x() + bs.width(), scrollbar.y(), scrollbar.width() - 2 * bs.width(), thickness);
+    } else {

[skobes, 2016/01/07 21:49:10]

Remove the "else" since we return in the if block.

[oshima, 2016/01/09 00:58:39]

Done.

+        thickness = scrollbar.width();
     }
     if (scrollbar.height() <= 2 * bs.height())
         return IntRect();