Support lossy and lossless <canvas>.toDataURL for webp

Source/platform/image-encoders/skia/WEBPImageEncoder.h

 /*
  * Copyright (c) 2011, 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 23 matching lines @@
 #include "wtf/Vector.h"
 
 class SkBitmap;
 
 namespace blink {
 
 struct ImageDataBuffer;
 
 class WEBPImageEncoder {
 public:
+    // For callers: control the compression mode: lossy or lossless.
+    enum Mode { Default = 0, Lossy = Default, Lossless };
+
     // Encode the input data with a compression quality in [0-100].
-    static bool encode(const SkBitmap&, int quality, Vector<unsigned char>*);
-    static bool encode(const ImageDataBuffer&, int quality, Vector<unsigned char>*);
+    static bool encode(const SkBitmap&, int quality, Vector<unsigned char>*, Mode = Default);
+    static bool encode(const ImageDataBuffer&, int quality, Vector<unsigned char>*, Mode = Default);
 
     // For callers: provide a reasonable compression quality default.
     enum Quality { DefaultCompressionQuality = 80 };
 };
 
 } // namespace blink
 
 #endif