fix multithread related crashes in skpdiff

tools/skpdiff/SkImageDiffer.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkImageDecoder.h"
 
 #include "SkImageDiffer.h"
 #include "skpdiff_util.h"
 
 const double SkImageDiffer::RESULT_CORRECT = 1.0f;
 const double SkImageDiffer::RESULT_INCORRECT = 0.0f;
 
 SkImageDiffer::SkImageDiffer()
     : fIsGood(true) {
 
 }
 
 SkImageDiffer::~SkImageDiffer() {
 
 }
-
-int SkImageDiffer::queueDiffOfFile(const char baseline[], const char test[]) {
-    SkBitmap baselineBitmap;
-    SkBitmap testBitmap;
-    if (!SkImageDecoder::DecodeFile(baseline, &baselineBitmap)) {
-        SkDebugf("Failed to load bitmap \"%s\"\n", baseline);
-        return -1;
-    }
-    if (!SkImageDecoder::DecodeFile(test, &testBitmap)) {
-        SkDebugf("Failed to load bitmap \"%s\"\n", test);
-        return -1;
-    }
-    return this->queueDiff(&baselineBitmap, &testBitmap);
-}