libwebp: update to v0.5.1

third_party/libwebp/dec/alphai.h

 // Copyright 2013 Google Inc. All Rights Reserved.
 //
 // Use of this source code is governed by a BSD-style license
 // that can be found in the COPYING file in the root of the source
 // tree. An additional intellectual property rights grant can be found
 // in the file PATENTS. All contributing project authors may
 // be found in the AUTHORS file in the root of the source tree.
 // -----------------------------------------------------------------------------
 //
 // Alpha decoder: internal header.
@@ skipping 14 matching lines @@
 
 typedef struct ALPHDecoder ALPHDecoder;
 struct ALPHDecoder {
   int width_;
   int height_;
   int method_;
   WEBP_FILTER_TYPE filter_;
   int pre_processing_;
   struct VP8LDecoder* vp8l_dec_;
   VP8Io io_;
-  int use_8b_decode;  // Although alpha channel requires only 1 byte per
-                      // pixel, sometimes VP8LDecoder may need to allocate
-                      // 4 bytes per pixel internally during decode.
+  int use_8b_decode_;  // Although alpha channel requires only 1 byte per
+                       // pixel, sometimes VP8LDecoder may need to allocate
+                       // 4 bytes per pixel internally during decode.
+  uint8_t* output_;
+  const uint8_t* prev_line_;   // last output row (or NULL)
 };
 
 //------------------------------------------------------------------------------
 // internal functions. Not public.
 
-// Allocates a new alpha decoder instance.
-ALPHDecoder* ALPHNew(void);
-
-// Clears and deallocates an alpha decoder instance.
-void ALPHDelete(ALPHDecoder* const dec);
+// Deallocate memory associated to dec->alpha_plane_ decoding
+void WebPDeallocateAlphaMemory(VP8Decoder* const dec);
 
 //------------------------------------------------------------------------------
 
 #ifdef __cplusplus
 }    // extern "C"
 #endif
 
 #endif  /* WEBP_DEC_ALPHAI_H_ */