Separate and update PDF_DIFF_TRACE_IN_PNG

experimental/PdfViewer/pdfparser/native/SkPdfNativeTokenizer.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 SkPdfNativeTokenizer_DEFINED
 #define SkPdfNativeTokenizer_DEFINED
 
@@ skipping 147 matching lines @@
 class SkPdfNativeTokenizer {
 public:
     SkPdfNativeTokenizer(SkPdfNativeObject* objWithStream,
                          SkPdfAllocator* allocator, SkPdfNativeDoc* doc);
     SkPdfNativeTokenizer(const unsigned char* buffer, int len,
                          SkPdfAllocator* allocator, SkPdfNativeDoc* doc);
 
     virtual ~SkPdfNativeTokenizer();
 
     // Reads one token. Returns false if there are no more tokens.
-    bool readToken(PdfToken* token);
+    // If writeDiff is true, and a token was read, create a PNG highlighting
+    // the difference caused by this command in /tmp/log_step_by_step.
+    // If PDF_TRACE_DIFF_IN_PNG is not defined, writeDiff does nothing.
+    bool readToken(PdfToken* token, bool writeDiff = false);
 
     // Put back a token to be read in the nextToken read. Only one token is allowed to be put
     // back. Must not necesaarely be the last token read.
     void PutBack(PdfToken token);
 
     // Reads the inline image that is present in the stream. At this point we just consumed the ID
     // token already.
     SkPdfImageDictionary* readInlineImage();
 
 private:
@@ skipping 10 matching lines @@
     bool fHasPutBack;
     PdfToken fPutBack;
 };
 
 const unsigned char* nextObject(const unsigned char* start, const unsigned char* end,
                                 SkPdfNativeObject* token,
                                 SkPdfAllocator* allocator,
                                 SkPdfNativeDoc* doc);
 
 #endif  // SkPdfNativeTokenizer_DEFINED