Update //third_party/protobuf to version 3.

third_party/protobuf/src/google/protobuf/stubs/once.cc

 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
-// http://code.google.com/p/protobuf/
+// https://developers.google.com/protocol-buffers/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 // copyright notice, this list of conditions and the following disclaimer
 // in the documentation and/or other materials provided with the
@@ skipping 41 matching lines @@
 void SchedYield() {
 #ifdef _WIN32
   Sleep(0);
 #else  // POSIX
   sched_yield();
 #endif
 }
 
 }  // namespace
 
+void GoogleOnceInit(ProtobufOnceType* once, void (*init_func)()) {
+  if (internal::Acquire_Load(once) != ONCE_STATE_DONE) {
+    internal::FunctionClosure0 func(init_func, false);
+    GoogleOnceInitImpl(once, &func);
+  }
+}
+
 void GoogleOnceInitImpl(ProtobufOnceType* once, Closure* closure) {
   internal::AtomicWord state = internal::Acquire_Load(once);
   // Fast path. The provided closure was already executed.
   if (state == ONCE_STATE_DONE) {
     return;
   }
   // The closure execution did not complete yet. The once object can be in one
   // of the two following states:
   //   - UNINITIALIZED: We are the first thread calling this function.
   //   - EXECUTING_CLOSURE: Another thread is already executing the closure.
@@ skipping 11 matching lines @@
     // Another thread has already started executing the closure. We need to
     // wait until it completes the initialization.
     while (state == ONCE_STATE_EXECUTING_CLOSURE) {
       // Note that futex() could be used here on Linux as an improvement.
       SchedYield();
       state = internal::Acquire_Load(once);
     }
   }
 }
 
-void GoogleOnceInit(ProtobufOnceType* once, void (*init_func)()) {
-  if (internal::Acquire_Load(once) != ONCE_STATE_DONE) {
-    internal::FunctionClosure0 func(init_func, false);
-    GoogleOnceInitImpl(once, &func);
-  }
-}
-
 }  // namespace protobuf
 }  // namespace google
 
 #endif  // GOOGLE_PROTOBUF_NO_THREAD_SAFETY