Checking if frame is complete and access duration doesn't need a decode

Source/core/platform/image-decoders/ImageDecoder.cpp

 /*
  * Copyright (C) 2008-2009 Torch Mobile, Inc.
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
@@ skipping 102 matching lines @@
         return adoptPtr(new WEBPImageDecoder(alphaOption, gammaAndColorProfileOption));
 
     if (matchesBMPSignature(contents))
         return adoptPtr(new BMPImageDecoder(alphaOption, gammaAndColorProfileOption));
 
     return nullptr;
 }
 
 bool ImageDecoder::frameHasAlphaAtIndex(size_t index) const
 {
-    if (m_frameBufferCache.size() <= index)
-        return true;
-    if (m_frameBufferCache[index].status() == ImageFrame::FrameComplete)
-        return m_frameBufferCache[index].hasAlpha();
-    return true;
+    return !frameIsCompleteAtIndex(index) || m_frameBufferCache[index].hasAlpha();
+}
+
+bool ImageDecoder::frameIsCompleteAtIndex(size_t index) const
+{
+    return (index < m_frameBufferCache.size()) &&
+        (m_frameBufferCache[index].status() == ImageFrame::FrameComplete);
 }
 
 unsigned ImageDecoder::frameBytesAtIndex(size_t index) const
 {
     if (m_frameBufferCache.size() <= index)
         return 0;
     // FIXME: Use the dimension of the requested frame.
     return m_size.area() * sizeof(ImageFrame::PixelData);
 }
 
@@ skipping 81 matching lines @@
 {
     return getScaledValue<LowerBound>(m_scaledRows, origY, searchStart);
 }
 
 int ImageDecoder::scaledY(int origY, int searchStart)
 {
     return getScaledValue<Exact>(m_scaledRows, origY, searchStart);
 }
 
 } // namespace WebCore