fix doc and code snippet for WebPINewDecoder() doc

Change-Id: I1a75fdf60f0b9f1816be28f22613438bfe21752b
diff --git a/src/webp/decode.h b/src/webp/decode.h
index 7a3bed9..4c5e74a 100644
--- a/src/webp/decode.h
+++ b/src/webp/decode.h
@@ -248,19 +248,19 @@
 // picture is only partially decoded, pending additional input.
 // Code example:
 //
-//   WebPInitDecBuffer(&buffer);
-//   buffer.colorspace = mode;
+//   WebPInitDecBuffer(&output_buffer);
+//   output_buffer.colorspace = mode;
 //   ...
-//   WebPIDecoder* idec = WebPINewDecoder(&buffer);
-//   while (has_more_data) {
-//     // ... (get additional data)
+//   WebPIDecoder* idec = WebPINewDecoder(&output_buffer);
+//   while (additional_data_is_available) {
+//     // ... (get additional data in some new_data[] buffer)
 //     status = WebPIAppend(idec, new_data, new_data_size);
-//     if (status != VP8_STATUS_SUSPENDED ||
-//       break;
+//     if (status != VP8_STATUS_OK && status != VP8_STATUS_SUSPENDED) {
+//       break;    // an error occurred.
 //     }
 //
 //     // The above call decodes the current available buffer.
-//     // Part of the image can now be refreshed by calling to
+//     // Part of the image can now be refreshed by calling
 //     // WebPIDecGetRGB()/WebPIDecGetYUVA() etc.
 //   }
 //   WebPIDelete(idec);