Scale scrollbar in use-zoom-for-dsf mode

third_party/WebKit/Source/core/page/ChromeClient.cpp

Index: third_party/WebKit/Source/core/page/ChromeClient.cpp
diff --git a/third_party/WebKit/Source/core/page/ChromeClient.cpp b/third_party/WebKit/Source/core/page/ChromeClient.cpp
index 5edee8ddfab1b61a466c3eab240d2344a2979a47..ae5565f2d1f388b9b0ae063946e49cbb16d840a6 100644
--- a/third_party/WebKit/Source/core/page/ChromeClient.cpp
+++ b/third_party/WebKit/Source/core/page/ChromeClient.cpp
@@ -191,4 +191,15 @@ void ChromeClient::print(LocalFrame* frame)
     printDelegate(frame);
 }
 
+float ChromeClient::screenToViewport(float length) const
+{
+    // Convert the thickness in the screen (dip) to the viewport by applying
+    // the invert of the viewport to screen scale.
+    // TODO(oshima): Add native implementation instead of using viewportToScreen.
+
+    IntRect inScreen(0, 0, 100, 0);
+    inScreen = viewportToScreen(inScreen);
+    return length * 100.f / inScreen.width();
+}
+
 } // namespace blink