First pass at Comment API

src/core/SkCanvas.cpp

Index: src/core/SkCanvas.cpp
===================================================================
--- src/core/SkCanvas.cpp	(revision 9288)
+++ src/core/SkCanvas.cpp	(working copy)
@@ -2010,10 +2010,6 @@
     LOOPER_END
 }
 
-void SkCanvas::drawData(const void* data, size_t length) {
-    // do nothing. Subclasses may do something with the data
-}
-
 //////////////////////////////////////////////////////////////////////////////
 // These methods are NOT virtual, and therefore must call back into virtual
 // methods, rather than actually drawing themselves.