Fix scrollbar painting problems in pdf files in HiDPI mode with fractional scales.

pdf/instance.cc

Index: pdf/instance.cc
diff --git a/pdf/instance.cc b/pdf/instance.cc
index 0ba1e6639b1702267ca7c924a77dbc2e4b3c2e79..50c2ba843a5e14d0231ce8ba4819d226c7bbba38 100644
--- a/pdf/instance.cc
+++ b/pdf/instance.cc
@@ -954,11 +954,6 @@ void Instance::PaintIfWidgetIntersects(
   DCHECK(!image_data_.is_null());
   widget->Paint(location_dip, &image_data_);
 
-  // Re-scale the rectangle from DIPs to device pixels, so we ensure that we
-  // don't miss any pixels due to rounding outwards in ScaleRect.
-  location = location_dip;
-  ScaleRect(device_scale_, &location);
-
   ready->push_back(PaintManager::ReadyRect(location, image_data_, true));
 }