Explicitly initialize secondary renderers for layout tests.

content/shell/browser/layout_test/layout_test_devtools_frontend.cc

Index: content/shell/browser/layout_test/layout_test_devtools_frontend.cc
diff --git a/content/shell/browser/layout_test/layout_test_devtools_frontend.cc b/content/shell/browser/layout_test/layout_test_devtools_frontend.cc
index fb17fca2b1604da85fe418a1f4a50d3c46739a2d..9b0064ef1d31ccc4f7981e540ae8c00a77950b1c 100644
--- a/content/shell/browser/layout_test/layout_test_devtools_frontend.cc
+++ b/content/shell/browser/layout_test/layout_test_devtools_frontend.cc
@@ -133,4 +133,15 @@ void LayoutTestDevToolsFrontend::RenderProcessGone(
   BlinkTestController::Get()->DevToolsProcessCrashed();
 }
 
+void LayoutTestDevToolsFrontend::RenderFrameCreated(
+    RenderFrameHost* render_frame_host) {
+  BlinkTestController::Get()->HandleNewRenderFrameHost(render_frame_host);
+}
+
+void LayoutTestDevToolsFrontend::RenderFrameHostChanged(
+    RenderFrameHost* old_host,
+    RenderFrameHost* new_host) {
+  BlinkTestController::Get()->HandleNewRenderFrameHost(new_host);
+}
+
 }  // namespace content