Update libwebp to 0.4.0

third_party/libwebp/utils/thread.h

 // Copyright 2011 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.
 // -----------------------------------------------------------------------------
 //
 // Multi-threaded worker
 //
 // Author: Skal (pascal.massimino@gmail.com)
 
 #ifndef WEBP_UTILS_THREAD_H_
 #define WEBP_UTILS_THREAD_H_
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
 
-#if defined(__cplusplus) || defined(c_plusplus)
+#ifdef __cplusplus
 extern "C" {
 #endif
 
-#if WEBP_USE_THREAD
+#ifdef WEBP_USE_THREAD
 
 #if defined(_WIN32)
 
 #include <windows.h>
 typedef HANDLE pthread_t;
 typedef CRITICAL_SECTION pthread_mutex_t;
 typedef struct {
   HANDLE waiting_sem_;
   HANDLE received_sem_;
   HANDLE signal_event_;
@@ skipping 12 matching lines @@
   OK,           // ready to work
   WORK          // busy finishing the current task
 } WebPWorkerStatus;
 
 // Function to be called by the worker thread. Takes two opaque pointers as
 // arguments (data1 and data2), and should return false in case of error.
 typedef int (*WebPWorkerHook)(void*, void*);
 
 // Synchronize object used to launch job in the worker thread
 typedef struct {
-#if WEBP_USE_THREAD
+#ifdef WEBP_USE_THREAD
   pthread_mutex_t mutex_;
   pthread_cond_t  condition_;
   pthread_t       thread_;
 #endif
   WebPWorkerStatus status_;
   WebPWorkerHook hook;    // hook to call
   void* data1;            // first argument passed to 'hook'
   void* data2;            // second argument passed to 'hook'
   int had_error;          // return value of the last call to 'hook'
 } WebPWorker;
 
 // Must be called first, before any other method.
 void WebPWorkerInit(WebPWorker* const worker);
 // Must be called to initialize the object and spawn the thread. Re-entrant.
 // Will potentially launch the thread. Returns false in case of error.
 int WebPWorkerReset(WebPWorker* const worker);
 // Makes sure the previous work is finished. Returns true if worker->had_error
 // was not set and no error condition was triggered by the working thread.
 int WebPWorkerSync(WebPWorker* const worker);
 // Triggers the thread to call hook() with data1 and data2 argument. These
 // hook/data1/data2 can be changed at any time before calling this function,
 // but not be changed afterward until the next call to WebPWorkerSync().
 void WebPWorkerLaunch(WebPWorker* const worker);
+// This function is similar to WebPWorkerLaunch() except that it calls the
+// hook directly instead of using a thread. Convenient to bypass the thread
+// mechanism while still using the WebPWorker structs. WebPWorkerSync() must
+// still be called afterward (for error reporting).
+void WebPWorkerExecute(WebPWorker* const worker);
 // Kill the thread and terminate the object. To use the object again, one
 // must call WebPWorkerReset() again.
 void WebPWorkerEnd(WebPWorker* const worker);
 
 //------------------------------------------------------------------------------
 
-#if defined(__cplusplus) || defined(c_plusplus)
+#ifdef __cplusplus
 }    // extern "C"
 #endif
 
 #endif  /* WEBP_UTILS_THREAD_H_ */