Cleanup: Delete deprecate/old API from WebCompositorSupport.

public/platform/WebCompositorSupport.h

Index: public/platform/WebCompositorSupport.h
diff --git a/public/platform/WebCompositorSupport.h b/public/platform/WebCompositorSupport.h
index 855fc1f57ad55077381753efcfd940926e59c57c..4335a353d57f5eb2b493d2a22497c01e3c50be56 100644
--- a/public/platform/WebCompositorSupport.h
+++ b/public/platform/WebCompositorSupport.h
@@ -77,9 +77,6 @@ public:
 
     virtual WebNinePatchLayer* createNinePatchLayer() { return 0; }
 
-    // TODO(dshwang): This isn't used anymore.
-    virtual WebSolidColorLayer* createSolidColorLayer() { return 0; }
-
     // The ownership of the WebScrollbarThemeGeometry pointer is passed to Chromium.
     virtual WebScrollbarLayer* createScrollbarLayer(WebScrollbar*, WebScrollbarThemePainter, WebScrollbarThemeGeometry*) { return 0; }