notify resource caches when pixelref genID goes stale

src/core/SkResourceCache.h

Index: src/core/SkResourceCache.h
diff --git a/src/core/SkResourceCache.h b/src/core/SkResourceCache.h
index 883ed189de2ede2094eb51ab8884fe2ea60fed5a..d2df35e7d511da17c1ba440c22b487d6617afabc 100644
--- a/src/core/SkResourceCache.h
+++ b/src/core/SkResourceCache.h
@@ -35,6 +35,8 @@ public:
         // length must be a multiple of 4
         void init(void* nameSpace, size_t length);
 
+        void* getNamespace() const { return fNamespace; }
+
         // This is only valid after having called init().
         uint32_t hash() const { return fHash; }
 
@@ -124,6 +126,13 @@ public:
     static size_t SetSingleAllocationByteLimit(size_t);
     static size_t GetSingleAllocationByteLimit();
 
+    /**
+     *  Visit all Rec that match the specified namespace:
+     *      true  : Rec is valid

[mtklein, 2015/01/07 21:52:43]

I think everything might read more clearly if we had true mean purge, false mean
keep.

[reed1, 2015/01/07 22:20:41]

I agree 0.499999, but Find uses the same VisitorProc and it treats false as
purge so .... (can't win)

[mtklein, 2015/01/08 14:11:12]

Do you think we'll ever want to pass the same function to both Find and
PurgeVisitor?  If it's super confusing they both take the same signature, we can
always just typedef another bool(*PurgeProc)(const Rec&, void*) with its own
note.

[reed1, 2015/02/18 17:30:32]

Changed to new signature.

+     *      false : Rec is "stale" -- the cache will purge it.
+     */
+    static void PurgeVisitor(const void* nameSpace, VisitorProc, void* context);
+
     static void PurgeAll();
 
     /**
@@ -193,6 +202,8 @@ public:
      */
     size_t setTotalByteLimit(size_t newLimit);
 
+    void purgeVisitor(const void* nameSpace, VisitorProc, void* context);
+
     void purgeAll() {
         this->purgeAsNeeded(true);
     }