Modify skpdiff to write diffs directly to provided directories

tools/skpdiff/SkDiffContext.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 SkDiffContext_DEFINED
 #define SkDiffContext_DEFINED
 
@@ skipping 34 matching lines @@
 
     /**
      * Sets the directory within which to store whiteDiffs (images showing white
      * for each pixel that differs between baseline and test).
      *
      * If the directory does not exist yet, it will be created.
      */
     void setWhiteDiffDir(const SkString& directory);
 
     /**
+     * Sets a flag wether to generate file names that a combination 
+     * of the baseline and test input files. 
+     * 
+     * If false the output file names are the common prefix of the 
+     * two inputs. 
+     */
+    void setLongNames(const bool useLongNames);
+
+    /**
      * Sets the differs to be used in each diff. Already started diffs will not retroactively use
      * these.
      * @param differs An array of differs to use. The array is copied, but not the differs
      *                themselves.
      */
     void setDiffers(const SkTDArray<SkImageDiffer*>& differs);
 
     /**
      * Compares two directories of images with the given differ
      * @param baselinePath The baseline directory's path
@@ skipping 105 matching lines @@
     // results.
     SkTLList<DiffRecord> fRecords;
 
     SkImageDiffer** fDiffers;
     int fDifferCount;
     int fThreadCount;
 
     SkString fAlphaMaskDir;
     SkString fRgbDiffDir;
     SkString fWhiteDiffDir;
+    bool longNames;
 };
 
 #endif