Add SkNWayCanvas comment API overrides.

src/utils/SkNWayCanvas.cpp

Index: src/utils/SkNWayCanvas.cpp
diff --git a/src/utils/SkNWayCanvas.cpp b/src/utils/SkNWayCanvas.cpp
index bfc7a7ab706ed88408da2f01f2a24947300d3d8b..5eebd01f453790727dfb835e055102b3fda7f4ae 100644
--- a/src/utils/SkNWayCanvas.cpp
+++ b/src/utils/SkNWayCanvas.cpp
@@ -311,3 +311,24 @@ SkDrawFilter* SkNWayCanvas::setDrawFilter(SkDrawFilter* filter) {
     }
     return this->INHERITED::setDrawFilter(filter);
 }
+
+void SkNWayCanvas::beginCommentGroup(const char* description) {
+    Iter iter(fList);
+    while (iter.next()) {
+        iter->beginCommentGroup(description);
+    }
+}
+
+void SkNWayCanvas::addComment(const char* kywd, const char* value) {
+    Iter iter(fList);
+    while (iter.next()) {
+        iter->addComment(kywd, value);
+    }
+}
+
+void SkNWayCanvas::endCommentGroup() {
+    Iter iter(fList);
+    while (iter.next()) {
+        iter->endCommentGroup();
+    }
+}