add assert that the lock-count on pixelref is balanced

src/core/SkPixelRef.cpp

 /*
  * Copyright 2011 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 "SkPixelRef.h"
 #include "SkThread.h"
 #include "SkTraceEvent.h"
 
+//#define SK_SUPPORT_LEGACY_UNBALANCED_PIXELREF_LOCKCOUNT
 //#define SK_TRACE_PIXELREF_LIFETIME
 
 #ifdef SK_BUILD_FOR_WIN32
     // We don't have SK_BASE_MUTEX_INIT on Windows.
 
     // must be a power-of-2. undef to just use 1 mutex
     #define PIXELREF_MUTEX_RING_COUNT       32
     static SkBaseMutex gPixelRefMutexRing[PIXELREF_MUTEX_RING_COUNT];
 
 #else
@@ skipping 100 matching lines @@
     this->setMutex(mutex);
     fRec.zero();
     fLockCount = 0;
     this->needsNewGenID();
     fIsImmutable = false;
     fPreLocked = false;
     fAddedToCache.store(false);
 }
 
 SkPixelRef::~SkPixelRef() {
+#ifndef SK_SUPPORT_LEGACY_UNBALANCED_PIXELREF_LOCKCOUNT
+    SkASSERT(SKPIXELREF_PRELOCKED_LOCKCOUNT == fLockCount || 0 == fLockCount);
+#endif
+
 #ifdef SK_TRACE_PIXELREF_LIFETIME
     SkDebugf("~pixelref %d\n", sk_atomic_dec(&gInstCounter) - 1);
 #endif
     this->callGenIDChangeListeners();
 }
 
 void SkPixelRef::needsNewGenID() {
     fTaggedGenID.store(0);
     SkASSERT(!this->genIDIsUnique()); // This method isn't threadsafe, so the assert should be fine.
 }
@@ skipping 153 matching lines @@
 
 bool SkPixelRef::onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3],
                                  SkYUVColorSpace* colorSpace) {
     return false;
 }
 
 size_t SkPixelRef::getAllocatedSizeInBytes() const {
     return 0;
 }