fix multithread related crashes in skpdiff

tools/skpdiff/SkImageDiffer.cpp

Index: tools/skpdiff/SkImageDiffer.cpp
diff --git a/tools/skpdiff/SkImageDiffer.cpp b/tools/skpdiff/SkImageDiffer.cpp
index 40a34da6b13443f6dbebca48887bba1f9cec63ab..62b1215dfce1f6108de5d8eedef8f94fbe853534 100644
--- a/tools/skpdiff/SkImageDiffer.cpp
+++ b/tools/skpdiff/SkImageDiffer.cpp
@@ -22,17 +22,3 @@ SkImageDiffer::SkImageDiffer()
 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);
-}