Add include guards for SkBRDAllocator

tools/android/SkBRDAllocator.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 SkBRDAllocator_DEFINED
+#define SkBRDAllocator_DEFINED
+
 #include "SkBitmap.h"
 #include "SkCodec.h"
 
 /**
  *  Abstract subclass of SkBitmap's allocator.
  *  Allows the allocator to indicate if the memory it allocates
  *  is zero initialized.
  */
 class SkBRDAllocator : public SkBitmap::Allocator {
 public:
 
     /**
      *  Indicates if the memory allocated by this allocator is
      *  zero initialized.
      */
     virtual SkCodec::ZeroInitialized zeroInit() const = 0;
 };
+
+#endif