private iterator to visit all resource cache entries

tests/ImageCacheTest.cpp

  /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDiscardableMemory.h"
 #include "SkResourceCache.h"
 #include "Test.h"
 
 namespace {
 static void* gGlobalAddress;
 struct TestingKey : public SkResourceCache::Key {
     intptr_t    fValue;
 
     TestingKey(intptr_t value, uint64_t sharedID = 0) : fValue(value) {
         this->init(&gGlobalAddress, sharedID, sizeof(fValue));
     }
 };
 struct TestingRec : public SkResourceCache::Rec {
     TestingRec(const TestingKey& key, uint32_t value) : fKey(key), fValue(value) {}
 
     TestingKey  fKey;
     intptr_t    fValue;
 
     const Key& getKey() const override { return fKey; }
     size_t bytesUsed() const override { return sizeof(fKey) + sizeof(fValue); }
+    const char* getCategory() const override { return "test_cache"; }
+    SkDiscardableMemory* diagnostic_only_getDiscardable() const override { return NULL; }
 
     static bool Visitor(const SkResourceCache::Rec& baseRec, void* context) {
         const TestingRec& rec = static_cast<const TestingRec&>(baseRec);
         intptr_t* result = (intptr_t*)context;
         
         *result = rec.fValue;
         return true;
     }
 };
 }
@@ skipping 103 matching lines @@
     TestingKey key(1);
 
     cache.add(SkNEW_ARGS(TestingRec, (key, 2)));
     cache.add(SkNEW_ARGS(TestingRec, (key, 3)));
 
     // Lookup can return either value.
     intptr_t value = -1;
     REPORTER_ASSERT(r, cache.find(key, TestingRec::Visitor, &value));
     REPORTER_ASSERT(r, 2 == value || 3 == value);
 }