Replace uses of GR_DEBUG by SK_DEBUG.

src/gpu/GrMemoryPool.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrMemoryPool.h"
 
-#if GR_DEBUG
+#ifdef SK_DEBUG
     #define VALIDATE this->validate()
 #else
     #define VALIDATE
 #endif
 
 GrMemoryPool::GrMemoryPool(size_t preallocSize, size_t minAllocSize) {
     GR_DEBUGCODE(fAllocationCnt = 0);
 
     minAllocSize = GrMax<size_t>(minAllocSize, 1 << 10);
     fMinAllocSize = GrSizeAlignUp(minAllocSize + kPerAllocPad, kAlignment),
@@ skipping 131 matching lines @@
             SkASSERT(userStart == block->fCurrPtr);
         } else {
             SkASSERT(block == *reinterpret_cast<BlockHeader**>(userStart));
         }
         prev = block;
     } while ((block = block->fNext));
     SkASSERT(allocCount == fAllocationCnt);
     SkASSERT(prev == fTail);
 #endif
 }