remove unused methods createNinePatchLayer() and setContentsToNinePatch()

public/platform/WebCompositorSupport.h

Index: public/platform/WebCompositorSupport.h
diff --git a/public/platform/WebCompositorSupport.h b/public/platform/WebCompositorSupport.h
index a69df3cdcbd458e53dbcf58888ba93688e5a82ee..5d8402c1709175fbe390ac331277ce29cc949b66 100644
--- a/public/platform/WebCompositorSupport.h
+++ b/public/platform/WebCompositorSupport.h
@@ -70,8 +70,6 @@ public:
 
     virtual WebImageLayer* createImageLayer() { return nullptr; }
 
-    virtual WebNinePatchLayer* createNinePatchLayer() { return nullptr; }
-
     // The ownership of the WebScrollbarThemeGeometry pointer is passed to Chromium.
     virtual WebScrollbarLayer* createScrollbarLayer(WebScrollbar*, WebScrollbarThemePainter, WebScrollbarThemeGeometry*) { return nullptr; }