Revert "third_party/protobuf: Update to HEAD (83d681ee2c)"

third_party/protobuf/src/google/protobuf/arenastring.h

Index: third_party/protobuf/src/google/protobuf/arenastring.h
diff --git a/third_party/protobuf/src/google/protobuf/arenastring.h b/third_party/protobuf/src/google/protobuf/arenastring.h
index d8bd580670174837148d5df6d5dc2c854853ede2..d983cf6ce50f3ffe85a16d98f56575344900535b 100755
--- a/third_party/protobuf/src/google/protobuf/arenastring.h
+++ b/third_party/protobuf/src/google/protobuf/arenastring.h
@@ -37,6 +37,7 @@
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/stubs/fastmem.h>
 #include <google/protobuf/arena.h>
+#include <google/protobuf/generated_message_util.h>
 
 
 
@@ -63,7 +64,9 @@ struct LIBPROTOBUF_EXPORT ArenaStringPtr {
   }
 
   // Basic accessors.
-  inline const ::std::string& Get() const { return *ptr_; }
+  inline const ::std::string& Get(const ::std::string* /* default_value */) const {
+    return *ptr_;
+  }
 
   inline ::std::string* Mutable(const ::std::string* default_value,
                            ::google::protobuf::Arena* arena) {
@@ -147,12 +150,13 @@ struct LIBPROTOBUF_EXPORT ArenaStringPtr {
     std::swap(ptr_, other->ptr_);
   }
 
-  // Frees storage (if not on an arena).
+  // Frees storage (if not on an arena) and sets field to default value.
   inline void Destroy(const ::std::string* default_value,
                       ::google::protobuf::Arena* arena) {
     if (arena == NULL && ptr_ != default_value) {
       delete ptr_;
     }
+    ptr_ = const_cast< ::std::string* >(default_value);
   }
 
   // Clears content, but keeps allocated string if arena != NULL, to avoid the
@@ -212,7 +216,9 @@ struct LIBPROTOBUF_EXPORT ArenaStringPtr {
 
   void AssignWithDefault(const ::std::string* default_value, ArenaStringPtr value);
 
-  inline const ::std::string& GetNoArena() const { return *ptr_; }
+  inline const ::std::string& GetNoArena(const ::std::string* /* default_value */) const {
+    return *ptr_;
+  }
 
   ::std::string* MutableNoArena(const ::std::string* default_value);
 
@@ -265,10 +271,6 @@ struct LIBPROTOBUF_EXPORT ArenaStringPtr {
     return &ptr_;
   }
 
-  inline bool IsDefault(const ::std::string* default_value) const {
-    return ptr_ == default_value;
-  }
-
  private:
   ::std::string* ptr_;