Update libwebp to 0.4.0

third_party/libwebp/dec/decode_vp8.h

 // Copyright 2010 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.
 // -----------------------------------------------------------------------------
 //
 //  Low-level API for VP8 decoder
 //
 // Author: Skal (pascal.massimino@gmail.com)
 
 #ifndef WEBP_WEBP_DECODE_VP8_H_
 #define WEBP_WEBP_DECODE_VP8_H_
 
 #include "../webp/decode.h"
 
-#if defined(__cplusplus) || defined(c_plusplus)
+#ifdef __cplusplus
 extern "C" {
 #endif
 
 //------------------------------------------------------------------------------
 // Lower-level API
 //
 // These functions provide fine-grained control of the decoding process.
 // The call flow should resemble:
 //
 //   VP8Io io;
@@ skipping 95 matching lines @@
 // Create a new decoder object.
 VP8Decoder* VP8New(void);
 
 // Must be called to make sure 'io' is initialized properly.
 // Returns false in case of version mismatch. Upon such failure, no other
 // decoding function should be called (VP8Decode, VP8GetHeaders, ...)
 static WEBP_INLINE int VP8InitIo(VP8Io* const io) {
   return VP8InitIoInternal(io, WEBP_DECODER_ABI_VERSION);
 }
 
-// Start decoding a new picture. Returns true if ok.
+// Decode the VP8 frame header. Returns true if ok.
+// Note: 'io->data' must be pointing to the start of the VP8 frame header.
 int VP8GetHeaders(VP8Decoder* const dec, VP8Io* const io);
 
 // Decode a picture. Will call VP8GetHeaders() if it wasn't done already.
 // Returns false in case of error.
 int VP8Decode(VP8Decoder* const dec, VP8Io* const io);
 
 // Return current status of the decoder:
 VP8StatusCode VP8Status(VP8Decoder* const dec);
 
 // return readable string corresponding to the last status.
@@ skipping 24 matching lines @@
 // Returns true if the next byte(s) in data is a VP8L signature.
 WEBP_EXTERN(int) VP8LCheckSignature(const uint8_t* const data, size_t size);
 
 // Validates the VP8L data-header and retrieves basic header information viz
 // width, height and alpha. Returns 0 in case of formatting error.
 // width/height/has_alpha can be passed NULL.
 WEBP_EXTERN(int) VP8LGetInfo(
     const uint8_t* data, size_t data_size,  // data available so far
     int* const width, int* const height, int* const has_alpha);
 
-#if defined(__cplusplus) || defined(c_plusplus)
+#ifdef __cplusplus
 }    // extern "C"
 #endif
 
 #endif  /* WEBP_WEBP_DECODE_VP8_H_ */