Implement InterpolationMedium to filter animated images

Source/platform/graphics/skia/NativeImageSkia.h

 /*
  * Copyright (c) 2008, 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 44 matching lines @@
 // Used by computeResamplingMode to tell how bitmaps should be resampled.
 enum ResamplingMode {
     // Nearest neighbor resampling. Used when we detect that the page is
     // trying to make a pattern by stretching a small bitmap very large.
     NoResampling,
 
     // Default skia resampling. Used for large growing of images where high
     // quality resampling doesn't get us very much except a slowdown.
     LinearResampling,
 
+    // LinearResampling for upscaling. Mipmapping for downscaling.
+    MediumResampling,

[Stephen White, 2014/03/18 17:26:43]

Bikeshed: maybe this should be LinearMipmaps or LinearWithMipmaps or something.
The other types in this enum refer to algorithms, while this seems to belong
more to high/medium/low.

[Alpha Left Google, 2014/03/18 22:59:13]

Done.

+
     // High quality resampling.
     AwesomeResampling,
 };
 
 // This object is used as the "native image" in our port. When WebKit uses
 // PassNativeImagePtr / NativeImagePtr, it is a smart pointer to this type.
 // It has an SkBitmap, and also stores a cached resized image.
 class PLATFORM_EXPORT NativeImageSkia : public RefCounted<NativeImageSkia> {
 public:
     static PassRefPtr<NativeImageSkia> create()
@@ skipping 121 matching lines @@
     // those requests individually are small and would not otherwise be cached.
     //
     // We also track scaling information and destination subset for the scaled
     // image. See comments for ImageResourceInfo.
     mutable ImageResourceInfo m_cachedImageInfo;
     mutable int m_resizeRequests;
 };
 
 }
 #endif  // NativeImageSkia_h