notify resource caches when pixelref genID goes stale

src/core/SkBitmapCache.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkBitmapCache_DEFINED
 #define SkBitmapCache_DEFINED
 
@@ skipping 30 matching lines @@
      */
     static bool Find(uint32_t genID, const SkIRect& subset, SkBitmap* result,
                      SkResourceCache* localCache = NULL);
 
     /**
      * The width and the height of the provided subset must be the same as the result bitmap ones.
      * result must be marked isImmutable()
      */
     static bool Add(uint32_t genID, const SkIRect& subset, const SkBitmap& result,
                     SkResourceCache* localCache = NULL);
+
+    /**
+     *  Call this to (as a hint) preemptively purge caches related to this genID
+     */
+    static void NotifyGenIDStale(uint32_t);
 };
 
 class SkMipMapCache {
 public:
     static const SkMipMap* FindAndRef(const SkBitmap& src, SkResourceCache* localCache = NULL);
     static const SkMipMap* AddAndRef(const SkBitmap& src, SkResourceCache* localCache = NULL);
+
+    /**
+     *  Call this to (as a hint) preemptively purge caches related to this genID
+     */
+    static void NotifyGenIDStale(uint32_t);
 };
 
 #endif