Sample for GPU memory dumping using new SkTraceMemoryDump.

src/core/SkTraceMemoryDump.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkTraceMemoryDump_DEFINED
 #define SkTraceMemoryDump_DEFINED
 
@@ skipping 40 matching lines @@
                                 const SkString &backingObjectId) = 0;
 
   /**
    * Specialization for memory backed by discardable memory.
    */
   virtual void SetDiscardableMemoryBacking(
       const SkString &dumpName,
       const SkDiscardableMemory &discardableMemoryObject) = 0;
 
 protected:
-  virtual ~SkTraceMemoryDump() = 0;
+  virtual ~SkTraceMemoryDump() {}
 };
 
 #endif