Ensure RemoteViewportIntersection rect persists across frame navigations

content/browser/frame_host/render_widget_host_view_child_frame.cc

Index: content/browser/frame_host/render_widget_host_view_child_frame.cc
diff --git a/content/browser/frame_host/render_widget_host_view_child_frame.cc b/content/browser/frame_host/render_widget_host_view_child_frame.cc
index b979394f565d7b93020fd3e2f94cbce8a0ddb9a9..cbd72586e4244e8d7bb4e0cbe291f49933a9830c 100644
--- a/content/browser/frame_host/render_widget_host_view_child_frame.cc
+++ b/content/browser/frame_host/render_widget_host_view_child_frame.cc
@@ -614,6 +614,11 @@ bool RenderWidgetHostViewChildFrame::IsRenderWidgetHostViewChildFrame() {
   return true;
 }
 
+void RenderWidgetHostViewChildFrame::WillSendScreenRects() {
+  if (frame_connector_)
+    UpdateViewportIntersection(frame_connector_->viewport_intersection());
+}
+
 #if defined(OS_MACOSX)
 ui::AcceleratedWidgetMac*
 RenderWidgetHostViewChildFrame::GetAcceleratedWidgetMac() const {