Fix two leaks & improve leak tracking

src/lazy/SkPurgeableImageCache.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 "SkThread.h"
 #include "SkPurgeableImageCache.h"
 #include "SkPurgeableMemoryBlock.h"
 
 #ifdef SK_DEBUG
     #include "SkTSearch.h"
 #endif
 
+SK_DEFINE_INST_COUNT(SkPurgeableImageCache)
 SK_DECLARE_STATIC_MUTEX(gPurgeableImageMutex);
 
 SkImageCache* SkPurgeableImageCache::Create() {
     if (!SkPurgeableMemoryBlock::IsSupported()) {
         return NULL;
     }
     SkAutoMutexAcquire ac(&gPurgeableImageMutex);
     static SkPurgeableImageCache gCache;
     gCache.ref();
     return &gCache;
@@ skipping 124 matching lines @@
 void SkPurgeableImageCache::removeRec(intptr_t ID) {
 #ifdef SK_DEBUG
     int index = this->findRec(ID);
     SkASSERT(index >= 0);
     fRecs.remove(index);
 #endif
     SkPurgeableMemoryBlock* block = reinterpret_cast<SkPurgeableMemoryBlock*>(ID);
     SkASSERT(!block->isPinned());
     SkDELETE(block);
 }