Retract SkPicture::kOptimizeForClippedPlayback_RecordingFlag from public API

src/core/SkPicture.cpp

Index: src/core/SkPicture.cpp
===================================================================
--- src/core/SkPicture.cpp	(revision 14216)
+++ src/core/SkPicture.cpp	(working copy)
@@ -253,6 +253,10 @@
 }
 
 SkBBoxHierarchy* SkPicture::createBBoxHierarchy() const {
+    // TODO: this code is now replicated in SkRTreePicture. Once all external
+    // clients have been weaned off of kOptimizeForClippedPlayback_RecordingFlag,
+    // this code can be removed.
+
     // These values were empirically determined to produce reasonable
     // performance in most cases.
     static const int kRTreeMinChildren = 6;