Pass implementation object to supplemental classes by reference

Source/core/rendering/RenderFullScreen.cpp

 /*
  * Copyright (C) 2010 Apple 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:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 58 matching lines @@
 {
     if (m_placeholder) {
         remove();
         if (!m_placeholder->beingDestroyed())
             m_placeholder->destroy();
         ASSERT(!m_placeholder);
     }
 
     // RenderObjects are unretained, so notify the document (which holds a pointer to a RenderFullScreen)
     // if it's RenderFullScreen is destroyed.
-    FullscreenElementStack* controller = FullscreenElementStack::from(&document());
-    if (controller->fullScreenRenderer() == this)
-        controller->fullScreenRendererDestroyed();
+    FullscreenElementStack& controller = FullscreenElementStack::from(document());
+    if (controller.fullScreenRenderer() == this)
+        controller.fullScreenRendererDestroyed();
 
     RenderFlexibleBox::willBeDestroyed();
 }
 
 static PassRefPtr<RenderStyle> createFullScreenStyle()
 {
     RefPtr<RenderStyle> fullscreenStyle = RenderStyle::createDefaultStyle();
 
     // Create a stacking context:
     fullscreenStyle->setZIndex(INT_MAX);
@@ skipping 41 matching lines @@
             // Always just do a full layout to ensure that line boxes get deleted properly.
             // Because objects moved from |parent| to |fullscreenRenderer|, we want to
             // make new line boxes instead of leaving the old ones around.
             parent->setNeedsLayoutAndPrefWidthsRecalc();
             containingBlock->setNeedsLayoutAndPrefWidthsRecalc();
         }
         fullscreenRenderer->addChild(object);
         fullscreenRenderer->setNeedsLayoutAndPrefWidthsRecalc();
     }
 
-    FullscreenElementStack::from(document)->setFullScreenRenderer(fullscreenRenderer);
+    ASSERT(document);
+    FullscreenElementStack::from(*document).setFullScreenRenderer(fullscreenRenderer);
     return fullscreenRenderer;
 }
 
 void RenderFullScreen::unwrapRenderer()
 {
     if (parent()) {
         RenderObject* child;
         while ((child = firstChild())) {
             // We have to clear the override size, because as a flexbox, we
             // may have set one on the child, and we don't want to leave that
             // lying around on the child.
             if (child->isBox())
                 toRenderBox(child)->clearOverrideSize();
             child->remove();
             parent()->addChild(child, this);
             parent()->setNeedsLayoutAndPrefWidthsRecalc();
         }
     }
     if (placeholder())
         placeholder()->remove();
     remove();
-    FullscreenElementStack::from(&document())->setFullScreenRenderer(0);
+    FullscreenElementStack::from(document()).setFullScreenRenderer(0);
 }
 
 void RenderFullScreen::setPlaceholder(RenderBlock* placeholder)
 {
     m_placeholder = placeholder;
 }
 
 void RenderFullScreen::createPlaceholder(PassRefPtr<RenderStyle> style, const LayoutRect& frameRect)
 {
     if (style->width().isAuto())
         style->setWidth(Length(frameRect.width(), Fixed));
     if (style->height().isAuto())
         style->setHeight(Length(frameRect.height(), Fixed));
 
     if (!m_placeholder) {
         m_placeholder = new RenderFullScreenPlaceholder(this);
         m_placeholder->setStyle(style);
         if (parent()) {
             parent()->addChild(m_placeholder, this);
             parent()->setNeedsLayoutAndPrefWidthsRecalc();
         }
     } else
         m_placeholder->setStyle(style);
 }