Reland r165710 "Replace RenderFullScreen with top layer"

Source/core/html/HTMLPlugInElement.cpp

Index: Source/core/html/HTMLPlugInElement.cpp
diff --git a/Source/core/html/HTMLPlugInElement.cpp b/Source/core/html/HTMLPlugInElement.cpp
index 0b2df23c31693eb216d32f4f308cd4248aba55c8..af98fe7cca34eb31ac548576c27345366cf6f35b 100644
--- a/Source/core/html/HTMLPlugInElement.cpp
+++ b/Source/core/html/HTMLPlugInElement.cpp
@@ -68,6 +68,7 @@ HTMLPlugInElement::HTMLPlugInElement(const QualifiedName& tagName, Document& doc
     , m_needsWidgetUpdate(!createdByParser)
     , m_shouldPreferPlugInsForImages(preferPlugInsForImagesOption == ShouldPreferPlugInsForImages)
     , m_displayState(Playing)
+    , m_protectWidgetDuringReattach(0)
 {
     setHasCustomStyleCallbacks();
 }
@@ -116,8 +117,19 @@ void HTMLPlugInElement::attach(const AttachContext& context)
 {
     HTMLFrameOwnerElement::attach(context);
 
+    if (m_protectWidgetDuringReattach) {
+        RenderEmbeddedObject* object = renderEmbeddedObject();
+        if (object && !needsWidgetUpdate()) {
+            object->setWidget(m_protectWidgetDuringReattach.get());
+            m_protectWidgetDuringReattach.clear();
+            return;
+        }
+        m_protectWidgetDuringReattach.clear();
+    }
+
     if (!renderer() || useFallbackContent())
         return;
+
     if (isImageType()) {
         if (!m_imageLoader)
             m_imageLoader = adoptPtr(new HTMLImageLoader(this));
@@ -146,8 +158,11 @@ void HTMLPlugInElement::detach(const AttachContext& context)
 {
     // Update the widget the next time we attach (detaching destroys the plugin).
     // FIXME: None of this "needsWidgetUpdate" related code looks right.
-    if (renderer() && !useFallbackContent())
+    if (context.performingReattach && renderEmbeddedObject() && !needsWidgetUpdate() && existingRenderWidget())
+        m_protectWidgetDuringReattach = existingRenderWidget()->widget();
+    else if (renderer() && !useFallbackContent())
         setNeedsWidgetUpdate(true);
+
     if (m_isDelayingLoadEvent) {
         m_isDelayingLoadEvent = false;
         document().decrementLoadEventDelayCount();