Use refs for non-null GraphicsContext, Scrollbar, etc. in scrollbar related code

third_party/WebKit/Source/core/layout/LayoutTextControl.cpp

 /**
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  *           (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 93 matching lines @@
 void LayoutTextControl::updateFromElement()
 {
     Element* innerEditor = innerEditorElement();
     if (innerEditor && innerEditor->layoutObject())
         updateUserModifyProperty(*textFormControlElement(), innerEditor->layoutObject()->mutableStyleRef());
 }
 
 int LayoutTextControl::scrollbarThickness() const
 {
     // FIXME: We should get the size of the scrollbar from the LayoutTheme instead.
-    return ScrollbarTheme::theme()->scrollbarThickness();
+    return ScrollbarTheme::theme().scrollbarThickness();
 }
 
 void LayoutTextControl::computeLogicalHeight(LayoutUnit logicalHeight, LayoutUnit logicalTop, LogicalExtentComputedValues& computedValues) const
 {
     HTMLElement* innerEditor = innerEditorElement();
     ASSERT(innerEditor);
     if (LayoutBox* innerEditorBox = innerEditor->layoutBox()) {
         LayoutUnit nonContentHeight = innerEditorBox->borderAndPaddingHeight() + innerEditorBox->marginHeight();
         logicalHeight = computeControlLogicalHeight(innerEditorBox->lineHeight(true, HorizontalLine, PositionOfInteriorLineBoxes), nonContentHeight);
 
@@ skipping 155 matching lines @@
     HTMLElement* placeholder = toHTMLTextFormControlElement(node())->placeholderElement();
     LayoutObject* placeholderLayoutObject = placeholder ? placeholder->layoutObject() : nullptr;
     if (!placeholderLayoutObject)
         return nullptr;
     if (relayoutChildren)
         layoutScope.setChildNeedsLayout(placeholderLayoutObject);
     return placeholderLayoutObject;
 }
 
 } // namespace blink