Fix more warnings on linux

Source/core/platform/graphics/chromium/ImageDecodingStore.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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 245 matching lines @@
     }
     prune();
 }
 
 size_t ImageDecodingStore::memoryUsageInBytes()
 {
     MutexLocker lock(m_mutex);
     return m_memoryUsageInBytes;
 }
 
-unsigned ImageDecodingStore::cacheEntries()
+int ImageDecodingStore::cacheEntries()
 {
     MutexLocker lock(m_mutex);
     return m_imageCacheMap.size() + m_decoderCacheMap.size();
 }
 
-unsigned ImageDecodingStore::imageCacheEntries()
+int ImageDecodingStore::imageCacheEntries()
 {
     MutexLocker lock(m_mutex);
     return m_imageCacheMap.size();
 }
 
-unsigned ImageDecodingStore::decoderCacheEntries()
+int ImageDecodingStore::decoderCacheEntries()
 {
     MutexLocker lock(m_mutex);
     return m_decoderCacheMap.size();
 }
 
 void ImageDecodingStore::prune()
 {
     TRACE_EVENT0("webkit", "ImageDecodingStore::prune");
 
     Vector<OwnPtr<CacheEntry> > cacheEntriesToDelete;
@@ skipping 111 matching lines @@
     }
 }
 
 void ImageDecodingStore::removeFromCacheListInternal(const Vector<OwnPtr<CacheEntry> >& deletionList)
 {
     for (size_t i = 0; i < deletionList.size(); ++i)
         m_orderedCacheList.remove(deletionList[i].get());
 }
 
 } // namespace WebCore