Fix clang 'overloaded-virtual' warnings.

This patch fixes the warning like the following:

../../src/animator/SkPaintParts.h:26:18: warning: 'SkPaintPart::add' hides overloaded virtual function [-Woverloaded-virtual]
virtual bool add() = 0;
             ^
../../src/animator/SkDisplayable.h:35:18: note: hidden overloaded virtual function 'SkDisplayable::add' declared here
virtual bool add(SkAnimateMaker& , SkDisplayable* child);
             ^

R=robertphillips@google.com,

Review URL: https://codereview.appspot.com/6843134

git-svn-id: http://skia.googlecode.com/svn/trunk@6642 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/animator/SkDrawGroup.h b/src/animator/SkDrawGroup.h
index a63a50e..336040c 100644
--- a/src/animator/SkDrawGroup.h
+++ b/src/animator/SkDrawGroup.h
@@ -19,7 +19,7 @@
     DECLARE_MEMBER_INFO(Group);
     SkGroup();
     virtual ~SkGroup();
-    virtual bool add(SkAnimateMaker& , SkDisplayable* child) SK_OVERRIDE;
+    virtual bool addChild(SkAnimateMaker& , SkDisplayable* child) SK_OVERRIDE;
     virtual bool contains(SkDisplayable* );
     SkGroup* copy();
     SkBool copySet(int index);