rebaseline_server: use just skpdiff, not Python Image Library

tools/skpdiff/SkPMetric.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPMetric_DEFINED
 #define SkPMetric_DEFINED
 
 #include "SkTArray.h"
 #include "SkTDArray.h"
 
 #include "SkImageDiffer.h"
 
 /**
  * An image differ that uses the pdiff image metric to compare images.
  */
 class SkPMetric : public SkImageDiffer {
 public:
     virtual const char* getName() const SK_OVERRIDE { return "perceptual"; }
-    virtual bool diff(SkBitmap* baseline, SkBitmap* test, bool computeMask,
+    virtual bool diff(SkBitmap* baseline, SkBitmap* test, const BitmapsToCreate& bitmapsToCreate,
                       Result* result) const SK_OVERRIDE;
 
 private:
     typedef SkImageDiffer INHERITED;
 };
 
 
 #endif