content: fix root-scroll coordinates

The coordinates need to be converted if zoom-for-dsf is enabled.

BUG=1119725
TEST=see description in bug.

Change-Id: Ic70a77cb726fb1458a1bbb5304d8ec518176901c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2370654Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801002}

content/browser/renderer_host/render_widget_host_view_android.cc

@@ -601,8 +601,12 @@ void RenderWidgetHostViewAndroid::
 
 void RenderWidgetHostViewAndroid::OnRootScrollOffsetChanged(
     const gfx::Vector2dF& root_scroll_offset) {
-  if (gesture_listener_manager_)
-    gesture_listener_manager_->OnRootScrollOffsetChanged(root_scroll_offset);
+  if (!gesture_listener_manager_)
+    return;
+  gfx::Vector2dF root_scroll_offset_dip = root_scroll_offset;
+  if (IsUseZoomForDSFEnabled())
+    root_scroll_offset_dip.Scale(1 / view_.GetDipScale());
+  gesture_listener_manager_->OnRootScrollOffsetChanged(root_scroll_offset_dip);
 }
 
 void RenderWidgetHostViewAndroid::Focus() {