unsigned -> int for counts and indices in picture-related code

tools/DumpRecord.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <stdio.h>
 
 #include "SkRecord.h"
@@ skipping 87 matching lines @@
     SkRecords::Draw fDraw;
     const bool fTimeWithCommand;
 };
 
 }  // namespace
 
 void DumpRecord(const SkRecord& record,
                   SkCanvas* canvas,
                   bool timeWithCommand) {
     Dumper dumper(canvas, record.count(), timeWithCommand);
-    for (unsigned i = 0; i < record.count(); i++) {
+    for (int i = 0; i < record.count(); i++) {
         record.visit<void>(i, dumper);
     }
 }