Resolve a few memory leaks in tests.

src/core/SkScaledImageCache.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 "SkScaledImageCache.h"
 #include "SkMipMap.h"
 #include "SkOnce.h"
@@ skipping 174 matching lines @@
 
     // One of these should be explicit set by the caller after we return.
     fByteLimit = 0;
     fDiscardableFactory = NULL;
 }
 
 #include "SkDiscardableMemory.h"
 
 class SkOneShotDiscardablePixelRef : public SkPixelRef {
 public:
+    SK_DECLARE_INST_COUNT(SkOneShotDiscardablePixelRef)
     // Ownership of the discardablememory is transfered to the pixelref
     SkOneShotDiscardablePixelRef(const SkImageInfo&, SkDiscardableMemory*, size_t rowBytes);
     ~SkOneShotDiscardablePixelRef();
 
     SK_DECLARE_UNFLATTENABLE_OBJECT()
 
 protected:
     virtual bool onNewLockPixels(LockRec*) SK_OVERRIDE;
     virtual void onUnlockPixels() SK_OVERRIDE;
     virtual size_t getAllocatedSizeInBytes() const SK_OVERRIDE;
@@ skipping 582 matching lines @@
     return SkScaledImageCache::GetBytesUsed();
 }
 
 size_t SkGraphics::GetImageCacheByteLimit() {
     return SkScaledImageCache::GetByteLimit();
 }
 
 size_t SkGraphics::SetImageCacheByteLimit(size_t newLimit) {
     return SkScaledImageCache::SetByteLimit(newLimit);
 }