Fixing stripe test

dm/DMSrcSink.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "DMSrcSink.h"
 #include "SamplePipeControllers.h"
 #include "SkCodec.h"
@@ skipping 313 matching lines @@
                         linesToRead, bitmap.rowBytes());
                 switch (result) {
                     case SkImageGenerator::kSuccess:
                     case SkImageGenerator::kIncompleteInput:
                         break;
                     default:
                         return SkStringPrintf("Cannot get scanlines for %s.", fPath.c_str());
                 }
 
                 // Skip a stripe
-                const int linesToSkip = SkTMax(0, SkTMin(stripeHeight,
-                        height - (i + 1) * stripeHeight));
-                result = decoder->skipScanlines(linesToSkip);
-                switch (result) {
-                    case SkImageGenerator::kSuccess:
-                    case SkImageGenerator::kIncompleteInput:
-                        break;
-                    default:
-                        return SkStringPrintf("Cannot skip scanlines for %s.", fPath.c_str());
+                const int linesToSkip = SkTMin(stripeHeight, height - (i + 1) * stripeHeight);
+                if (linesToSkip > 0) {
+                    result = decoder->skipScanlines(linesToSkip);
+                    switch (result) {
+                        case SkImageGenerator::kSuccess:
+                        case SkImageGenerator::kIncompleteInput:
+                            break;
+                        default:
+                            return SkStringPrintf("Cannot skip scanlines for %s.", fPath.c_str());
+                    }
                 }
             }
             canvas->drawBitmap(bitmap, 0, 0);
         }
     }
     return "";
 }
 
 SkISize CodecSrc::size() const {
     SkAutoTUnref<SkData> encoded(SkData::NewFromFileName(fPath.c_str()));
@@ skipping 616 matching lines @@
             skr.visit<void>(i, drawsAsSingletonPictures);
         }
         SkAutoTUnref<SkPicture> macroPic(macroRec.endRecordingAsPicture());
 
         canvas->drawPicture(macroPic);
         return "";
     });
 }
 
 }  // namespace DM