notify resource caches when pixelref genID goes stale

src/core/SkBitmapCache.h

Index: src/core/SkBitmapCache.h
diff --git a/src/core/SkBitmapCache.h b/src/core/SkBitmapCache.h
index ec8a6b803e9cf69196053a45213565c004c401d3..abda1b4d6692ef9cf64840b486ef0753b317fa12 100644
--- a/src/core/SkBitmapCache.h
+++ b/src/core/SkBitmapCache.h
@@ -48,12 +48,22 @@ public:
      */
     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