rename SkDrawable to SkADrawable

BUG=skia:

Review URL: https://codereview.chromium.org/764463002
diff --git a/src/animator/SkAnimateBase.cpp b/src/animator/SkAnimateBase.cpp
index 8467ce6..3515ed5 100644
--- a/src/animator/SkAnimateBase.cpp
+++ b/src/animator/SkAnimateBase.cpp
@@ -12,7 +12,7 @@
 #include "SkAnimateProperties.h"
 #include "SkAnimatorScript.h"
 #include "SkDisplayApply.h"
-#include "SkDrawable.h"
+#include "SkADrawable.h"
 
 #if SK_USE_CONDENSED_INFO == 0