private iterator to visit all resource cache entries

src/core/SkYUVPlanesCache.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapCache.h"
 #include "SkResourceCache.h"
 #include "SkYUVPlanesCache.h"
@@ skipping 30 matching lines @@
     }
     ~YUVPlanesRec() {
         fValue.fData->detachFromCacheAndUnref();
     }
 
     YUVPlanesKey  fKey;
     YUVValue      fValue;
 
     const Key& getKey() const override { return fKey; }
     size_t bytesUsed() const override { return sizeof(*this) + fValue.fData->size(); }
+    const char* getCategory() const override { return "yuv-planes"; }
+    SkDiscardableMemory* diagnostic_only_getDiscardable() const override {
+        return fValue.fData->diagnostic_only_getDiscardable();
+    }
 
     static bool Visitor(const SkResourceCache::Rec& baseRec, void* contextData) {
         const YUVPlanesRec& rec = static_cast<const YUVPlanesRec&>(baseRec);
         YUVValue* result = static_cast<YUVValue*>(contextData);
 
         SkCachedData* tmpData = rec.fValue.fData;
         tmpData->ref();
         if (NULL == tmpData->data()) {
             tmpData->unref();
             return false;
@@ skipping 15 matching lines @@
     
     *info = result.fInfo;
     return result.fData;
 }
 
 void SkYUVPlanesCache::Add(uint32_t genID, SkCachedData* data, Info* info,
                            SkResourceCache* localCache) {
     YUVPlanesKey key(genID);
     return CHECK_LOCAL(localCache, add, Add, SkNEW_ARGS(YUVPlanesRec, (key, data, info)));
 }