Copy SharedBuffer before calling decodeImageData

Source/web/ImageDecodeBench.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifdef WTF
 
 Provides a minimal wrapping of the Blink image decoders. Used to perform
 a non-threaded, memory-to-memory image decode using micro second accuracy
 clocks to measure image decode time. Optionally applies color correction
 during image decoding on supported platforms (default off). Usage:
@@ skipping 347 matching lines @@
     if (!data.get() || !data->size()) {
         fprintf(stderr, "Error reading image data from [%s]\n", argv[1]);
         exit(2);
     }
 
     // Image decode bench for iterations.
 
     double totalTime = 0.0;
 
     for (size_t i = 0; i < iterations; ++i) {
+        // Copy the SharedBuffer. Note that we do not want to call
+        // SharedBuffer::copy, which would merge all the segments. We want this
+        // to look just like it would receiving partial data off the web.
+        // After this call, data will have its segments merged, but not tempData.
+        RefPtr<SharedBuffer> tempData = SharedBuffer::create(data->data(), data->size());
+
         double startTime = getCurrentTime();
-        bool decoded = decodeImageData(data.get(), applyColorCorrection);
+        bool decoded = decodeImageData(tempData.get(), applyColorCorrection);
         double elapsedTime = getCurrentTime() - startTime;
         totalTime += elapsedTime;
         if (!decoded) {
             fprintf(stderr, "Image decode failed [%s]\n", argv[1]);
             exit(3);
         }
     }
 
     // Results to stdout.
 
     double averageTime = totalTime / static_cast<double>(iterations);
     printf("%f %f\n", totalTime, averageTime);
     return 0;
 }