Use a boolean hasCompositedLayerMapping() accessor instead of the pointer

Source/web/tests/ScrollingCoordinatorChromiumTest.cpp

Index: Source/web/tests/ScrollingCoordinatorChromiumTest.cpp
diff --git a/Source/web/tests/ScrollingCoordinatorChromiumTest.cpp b/Source/web/tests/ScrollingCoordinatorChromiumTest.cpp
index 46af6339d7c2bb31c52a255921a492e58d1a07c0..ed7ed891da726df56fd704068286eaf932b7f579 100644
--- a/Source/web/tests/ScrollingCoordinatorChromiumTest.cpp
+++ b/Source/web/tests/ScrollingCoordinatorChromiumTest.cpp
@@ -160,9 +160,11 @@ static WebLayer* webLayerFromElement(Element* element)
     RenderLayer* layer = toRenderBoxModelObject(renderer)->layer();
     if (!layer)
         return 0;
-    CompositedLayerMapping* compositedLayerMapping = layer->compositedLayerMapping();
-    if (!compositedLayerMapping)
+
+    if (!layer->hasCompositedLayerMapping())
         return 0;
+    CompositedLayerMapping* compositedLayerMapping = layer->compositedLayerMapping();
+
     GraphicsLayer* graphicsLayer = compositedLayerMapping->mainGraphicsLayer();
     if (!graphicsLayer)
         return 0;
@@ -305,6 +307,7 @@ TEST_F(ScrollingCoordinatorChromiumTest, overflowScrolling)
     RenderBox* box = toRenderBox(renderer);
     ASSERT_TRUE(box->usesCompositedScrolling());
     ASSERT_EQ(PaintsIntoOwnBacking, box->layer()->compositingState());
+    ASSERT_TRUE(box->layer()->hasCompositedLayerMapping());
 
     CompositedLayerMapping* compositedLayerMapping = box->layer()->compositedLayerMapping();
     ASSERT_TRUE(compositedLayerMapping->hasScrollingLayer());
@@ -345,6 +348,7 @@ TEST_F(ScrollingCoordinatorChromiumTest, overflowHidden)
     RenderBox* box = toRenderBox(renderer);
     ASSERT_TRUE(box->usesCompositedScrolling());
     ASSERT_EQ(PaintsIntoOwnBacking, box->layer()->compositingState());
+    ASSERT_TRUE(box->layer()->hasCompositedLayerMapping());
 
     CompositedLayerMapping* compositedLayerMapping = box->layer()->compositedLayerMapping();
     ASSERT_TRUE(compositedLayerMapping->hasScrollingLayer());
@@ -368,6 +372,7 @@ TEST_F(ScrollingCoordinatorChromiumTest, overflowHidden)
     box = toRenderBox(renderer);
     ASSERT_TRUE(box->scrollableArea()->usesCompositedScrolling());
     ASSERT_EQ(PaintsIntoOwnBacking, box->layer()->compositingState());
+    ASSERT_TRUE(box->layer()->hasCompositedLayerMapping());
 
     compositedLayerMapping = box->layer()->compositedLayerMapping();
     ASSERT_TRUE(compositedLayerMapping->hasScrollingLayer());