Use ScaleToEnclosingRect when converting the viewport to window.

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index c9e985fad75c4b9c652c2f98d429a97ecca5f54f..f590cfa7689141d617bc8c3b0e7feded4733294a 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -1515,15 +1515,10 @@ void RenderWidget::UpdateCompositionInfo(bool immediate_request) {
 
 void RenderWidget::convertViewportToWindow(blink::WebRect* rect) {
   if (IsUseZoomForDSFEnabled()) {
-    float reverse = 1 / GetOriginalDeviceScaleFactor();
     // TODO(oshima): We may need to allow pixel precision here as the the
     // anchor element can be placed at half pixel.
-    gfx::Rect window_rect =
-        gfx::ScaleToEnclosedRect(gfx::Rect(*rect), reverse);
-    rect->x = window_rect.x();
-    rect->y = window_rect.y();
-    rect->width = window_rect.width();
-    rect->height = window_rect.height();
+    *rect =
+        gfx::ScaleToEnclosingRect(*rect, 1.f / GetOriginalDeviceScaleFactor());
   }
 }