Implement pointer lock across outer/inner WebContents.

content/browser/renderer_host/render_widget_host_delegate.cc

Index: content/browser/renderer_host/render_widget_host_delegate.cc
diff --git a/content/browser/renderer_host/render_widget_host_delegate.cc b/content/browser/renderer_host/render_widget_host_delegate.cc
index 606370d90316cc8d39173b6b4dbb8fa35a82d5c4..d2740e3b8b8d2c16163d99525451b1e709ac6c93 100644
--- a/content/browser/renderer_host/render_widget_host_delegate.cc
+++ b/content/browser/renderer_host/render_widget_host_delegate.cc
@@ -99,4 +99,8 @@ bool RenderWidgetHostDelegate::AddDomainInfoToRapporSample(
   return false;
 }
 
+WebContents* RenderWidgetHostDelegate::GetAsWebContents() {
+  return nullptr;
+}
+
 }  // namespace content