Fix errors caused by unsafe conversions to/from size_t

third_party/WebKit/Source/platform/graphics/ImageFrameGeneratorTest.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 79 matching lines @@
     float frameDuration() const override { return 0; }
 
 protected:
     void useMockImageDecoderFactory()
     {
         m_generator->setImageDecoderFactory(MockImageDecoderFactory::create(this, fullSize()));
     }
 
     void addNewData(bool allDataReceived = false)
     {
-        m_data->append("g", 1);
+        m_data->append("g", 1u);
         m_generator->setData(m_data, allDataReceived);
     }
 
     void setFrameStatus(ImageFrame::Status status)  { m_status = m_nextFrameStatus = status; }
     void setNextFrameStatus(ImageFrame::Status status)  { m_nextFrameStatus = status; }
     void setFrameCount(size_t count)
     {
         m_frameCount = count;
         if (count > 1) {
             m_generator.clear();
@@ skipping 154 matching lines @@
 
     setFrameStatus(ImageFrame::FrameComplete);
 
     // Multi frame decoder should be removed.
     m_generator->decodeAndScale(2, imageInfo(), buffer, 100 * 4);
     EXPECT_EQ(3, m_decodeRequestCount);
     EXPECT_EQ(1, m_decodersDestroyed);
 }
 
 } // namespace blink