Fix CC*Renderer and CC*LayerImpl to compile with Clang

cc/CCScrollbarLayerImpl.cpp

Index: cc/CCScrollbarLayerImpl.cpp
diff --git a/cc/CCScrollbarLayerImpl.cpp b/cc/CCScrollbarLayerImpl.cpp
index b62d5cb6a06fd22e7a6631c502900d3dc812ee5b..63be4f531cf7ec08462fac874bd541caab3c52ef 100644
--- a/cc/CCScrollbarLayerImpl.cpp
+++ b/cc/CCScrollbarLayerImpl.cpp
@@ -41,6 +41,10 @@ CCScrollbarLayerImpl::CCScrollbarLayerImpl(int id)
 {
 }
 
+CCScrollbarLayerImpl::~CCScrollbarLayerImpl()
+{
+}
+
 void CCScrollbarLayerImpl::setScrollbarGeometry(PassOwnPtr<CCScrollbarGeometryFixedThumb> geometry)
 {
     m_geometry = geometry;
@@ -191,5 +195,11 @@ bool CCScrollbarLayerImpl::CCScrollbar::isCustomScrollbar() const
     return m_owner->m_isCustomScrollbar;
 }
 
+const char* CCScrollbarLayerImpl::layerTypeAsString() const
+{
+    return "ScrollbarLayer";
 }
+
+}
+
 #endif // USE(ACCELERATED_COMPOSITING)