Update libwebp to 0.4.0

third_party/libwebp/dec/io.c

Index: third_party/libwebp/dec/io.c
diff --git a/third_party/libwebp/dec/io.c b/third_party/libwebp/dec/io.c
index 63810b4472805278040f5c9fbbc547f6911b85e4..1ba376ed27e0dbb2a8fee895aa6a91e592fb78ce 100644
--- a/third_party/libwebp/dec/io.c
+++ b/third_party/libwebp/dec/io.c
@@ -18,10 +18,6 @@
 #include "../dsp/dsp.h"
 #include "../dsp/yuv.h"
 
-#if defined(__cplusplus) || defined(c_plusplus)
-extern "C" {
-#endif
-
 //------------------------------------------------------------------------------
 // Main YUV<->RGB conversion functions
 
@@ -119,7 +115,7 @@ static int EmitFancyRGB(const VP8Io* const io, WebPDecParams* const p) {
 
   if (y == 0) {
     // First line is special cased. We mirror the u/v samples at boundary.
-    upsample(NULL, cur_y, cur_u, cur_v, cur_u, cur_v, NULL, dst, mb_w);
+    upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v, dst, NULL, mb_w);
   } else {
     // We can finish the left-over line from previous call.
     upsample(p->tmp_y, cur_y, top_u, top_v, cur_u, cur_v,
@@ -603,7 +599,7 @@ static int CustomPut(const VP8Io* io) {
     return 0;
   }
   num_lines_out = p->emit(io, p);
-  if (p->emit_alpha) {
+  if (p->emit_alpha != NULL) {
     p->emit_alpha(io, p);
   }
   p->last_y += num_lines_out;
@@ -630,6 +626,3 @@ void WebPInitCustomIo(WebPDecParams* const params, VP8Io* const io) {
 
 //------------------------------------------------------------------------------
 
-#if defined(__cplusplus) || defined(c_plusplus)
-}    // extern "C"
-#endif