Use a boolean hasCompositedLayerMapping() accessor instead of the pointer

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index c13e919d26243d464040c1eb6e1e94da29162bf6..a35c0c5c8e69bc442cb378cbec4b374aff68bf68 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -2069,7 +2069,7 @@ bool FrameView::isTransparent() const
 void FrameView::setTransparent(bool isTransparent)
 {
     m_isTransparent = isTransparent;
-    if (renderView() && renderView()->layer()->compositedLayerMapping())
+    if (renderView() && renderView()->layer()->hasCompositedLayerMapping())
         renderView()->layer()->compositedLayerMapping()->updateContentsOpaque();
 }
 
@@ -2090,7 +2090,8 @@ void FrameView::setBaseBackgroundColor(const Color& backgroundColor)
     else
         m_baseBackgroundColor = backgroundColor;
 
-    if (CompositedLayerMapping* compositedLayerMapping = renderView() ? renderView()->layer()->compositedLayerMapping() : 0) {
+    if (renderView() && renderView()->layer()->hasCompositedLayerMapping()) {
+        CompositedLayerMappingPtr compositedLayerMapping = renderView()->layer()->compositedLayerMapping();
         compositedLayerMapping->updateContentsOpaque();
         if (compositedLayerMapping->mainGraphicsLayer())
             compositedLayerMapping->mainGraphicsLayer()->setNeedsDisplay();