Scale the scroll offset from viewport to dip in use-zoom-for-dsf mode.

content/renderer/pepper/pepper_plugin_instance_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/pepper/pepper_plugin_instance_impl.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bit_cast.h"
@@ skipping 1267 matching lines @@
       container_->pageZoomFactor() * container_->pageScaleFactor();
   blink::WebFloatRect windowToViewportScale(0, 0, 1.0f, 0);
   render_frame()->GetRenderWidget()->convertWindowToViewport(
       &windowToViewportScale);
   viewport_to_dip_scale_ = 1.0f / windowToViewportScale.width;
   ConvertRectToDIP(&view_data_.rect);
   ConvertRectToDIP(&view_data_.clip_rect);
   view_data_.css_scale *= viewport_to_dip_scale_;
   view_data_.device_scale /= viewport_to_dip_scale_;
 
-  gfx::Size scroll_offset =
-      container_->document().frame()->scrollOffset();
+  gfx::Size scroll_offset = gfx::ScaleToRoundedSize(
+      container_->document().frame()->scrollOffset(), viewport_to_dip_scale_);
+
   view_data_.scroll_offset = PP_MakePoint(scroll_offset.width(),
                                           scroll_offset.height());
 
   if (desired_fullscreen_state_ || view_data_.is_fullscreen) {
     WebElement element = container_->element();
     WebDocument document = element.document();
     bool is_fullscreen_element = (element == document.fullScreenElement());
     if (!view_data_.is_fullscreen && desired_fullscreen_state_ &&
         render_frame()->GetRenderWidget()->is_fullscreen_granted() &&
         is_fullscreen_element) {
@@ skipping 2109 matching lines @@
     const cc::TextureMailbox& mailbox) const {
   auto it =
       std::find_if(texture_ref_counts_.begin(), texture_ref_counts_.end(),
                    [&mailbox](const TextureMailboxRefCount& ref_count) {
                      return ref_count.first.mailbox() == mailbox.mailbox();
                    });
   return it != texture_ref_counts_.end();
 }
 
 }  // namespace content