rename SkDrawable to SkADrawable

BUG=skia:

Review URL: https://codereview.chromium.org/764463002
diff --git a/src/animator/SkDrawExtraPathEffect.cpp b/src/animator/SkDrawExtraPathEffect.cpp
index 007fb52..19b9df9 100644
--- a/src/animator/SkDrawExtraPathEffect.cpp
+++ b/src/animator/SkDrawExtraPathEffect.cpp
@@ -23,8 +23,8 @@
     virtual bool addChild(SkAnimateMaker& , SkDisplayable* ) SK_OVERRIDE;
     virtual SkPathEffect* getPathEffect();
 protected:
-    SkDrawable* addPath;
-    SkDrawable* addMatrix;
+    SkADrawable* addPath;
+    SkADrawable* addMatrix;
     SkDrawPath* path;
     SkPathEffect* fPathEffect;
     friend class SkShape1DPathEffect;