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 5532e49ff4cf692897901581be6047b9f8e3a74f..0e3c7c0a3ef0572049da9078388caca395df9983 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 {