Implement vertex buffer caching in the tessellated path renderer.

src/core/SkPathPriv.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPathPriv_DEFINED
 #define SkPathPriv_DEFINED
 
@@ skipping 41 matching lines @@
     static bool CheapIsFirstDirection(const SkPath& path, FirstDirection dir) {
         FirstDirection computedDir = kUnknown_FirstDirection;
         (void)CheapComputeFirstDirection(path, &computedDir);
         return computedDir == dir;
     }
 
     static bool LastVerbIsClose(const SkPath& path) {
         int count = path.countVerbs();
         return count >= 1 && path.fPathRef->verbs()[~(count - 1)] == SkPath::Verb::kClose_Verb;
     }
+
+    static void AddGenIDChangeListener(const SkPath& path, SkPathRef::GenIDChangeListener* listener) {
+        path.fPathRef->addGenIDChangeListener(listener);
+    }
 };
 
 #endif