update ChangeLog

Change-Id: I05b9ac2cf8fdd26e3f2e68780dca3e613bc2f732

ChangeLog

@@ -1,3 +1,5 @@
+deb54d9 Clarify the expected 'config' lifespan in WebPIDecode()
+c7e2d24 update ChangeLog (tag: v0.5.1-rc5)
 c7eb06f Fix corner case in CostManagerInit.
 ab7937a gif2webp: normalize the number of .'s in the help message
 3cdec84 vwebp: normalize the number of .'s in the help message

src/webp/decode.h

@@ -471,16 +471,18 @@ static WEBP_INLINE int WebPInitDecoderConfig(WebPDecoderConfig* config) {
 // parameter, in which case the features will be parsed and stored into
 // config->input. Otherwise, 'data' can be NULL and no parsing will occur.
 // Note that 'config' can be NULL too, in which case a default configuration
-// is used.
+// is used. If 'config' is not NULL, it must outlive the WebPIDecoder object
+// as some references to its fields will be used. No internal copy of 'config'
+// is made.
 // The return WebPIDecoder object must always be deleted calling WebPIDelete().
 // Returns NULL in case of error (and config->status will then reflect
-// the error condition).
+// the error condition, if available).
 WEBP_EXTERN(WebPIDecoder*) WebPIDecode(const uint8_t* data, size_t data_size,
                                        WebPDecoderConfig* config);
 
 // Non-incremental version. This version decodes the full data at once, taking
 // 'config' into account. Returns decoding status (which should be VP8_STATUS_OK
-// if the decoding was successful).
+// if the decoding was successful). Note that 'config' cannot be NULL.
 WEBP_EXTERN(VP8StatusCode) WebPDecode(const uint8_t* data, size_t data_size,
                                       WebPDecoderConfig* config);