Don't bother layout until first navigation is done.

third_party/WebKit/Source/core/testing/DummyPageHolder.cpp

 /*
  * Copyright (c) 2013, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 18 matching lines @@
  */
 
 #include "core/testing/DummyPageHolder.h"
 
 #include "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/loader/EmptyClients.h"
+#include "core/loader/FrameLoaderStateMachine.h"
 #include "wtf/Assertions.h"
 
 namespace blink {
 
 void RootLayerScrollsFrameSettingOverride(Settings& settings)
 {
     settings.setRootLayerScrolls(true);
 }
 
 PassOwnPtr<DummyPageHolder> DummyPageHolder::create(
@@ skipping 29 matching lines @@
         (*settingOverrider)(settings);
 
     m_frameLoaderClient = frameLoaderClient;
     if (!m_frameLoaderClient)
         m_frameLoaderClient = EmptyFrameLoaderClient::create();
 
     m_frame = LocalFrame::create(m_frameLoaderClient.get(), &m_page->frameHost(), 0);
     m_frame->setView(FrameView::create(m_frame.get(), initialViewSize));
     m_frame->view()->page()->frameHost().visualViewport().setSize(initialViewSize);
     m_frame->init();
+    // Some tests directly inject content into the initial empty document.
+    // Unmark it so that unforced layout would also run on the document.
+    m_frame->loader().stateMachine()->advanceTo(FrameLoaderStateMachine::CommittedFirstRealLoad);
 }
 
 DummyPageHolder::~DummyPageHolder()
 {
     m_page->willBeDestroyed();
     m_page.clear();
     m_frame.clear();
 }
 
 Page& DummyPageHolder::page() const
@@ skipping 11 matching lines @@
 {
     return *m_frame->view();
 }
 
 Document& DummyPageHolder::document() const
 {
     return *m_frame->domWindow()->document();
 }
 
 } // namespace blink