Fix more warnings on linux

Source/core/platform/graphics/chromium/ImageDecodingStore.h

 /*
  * 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 98 matching lines @@
 
     // Locks the cache for safety, but does not attempt to lock the object we're checking for.
     bool isCached(const ImageFrameGenerator*, const SkISize& scaledSize, size_t index);
 
     // Remove all cache entries indexed by ImageFrameGenerator.
     void removeCacheIndexedByGenerator(const ImageFrameGenerator*);
 
     void clear();
     void setCacheLimitInBytes(size_t);
     size_t memoryUsageInBytes();
-    unsigned cacheEntries();
-    unsigned imageCacheEntries();
-    unsigned decoderCacheEntries();
+    int cacheEntries();
+    int imageCacheEntries();
+    int decoderCacheEntries();
 
 private:
     // Image cache entry is identified by:
     // 1. Pointer to ImageFrameGenerator.
     // 2. Size of the image.
     // 3. Frame index.
     // 4. Frame generation. Increments on each progressive decode.
     //
     // The use of generation ID is to allow multiple versions of an image frame
     // be stored in the cache. Each generation comes from a progressive decode.
@@ skipping 182 matching lines @@
     //   m_cacheLimitInBytes
     //   m_memoryUsageInBytes
     // This mutex also protects calls to underlying skBitmap's
     // lockPixels()/unlockPixels() as they are not threadsafe.
     Mutex m_mutex;
 };
 
 } // namespace WebCore
 
 #endif