third_party/protobuf: Update to HEAD (83d681ee2c)

third_party/protobuf/src/google/protobuf/util/field_mask_util.h

Index: third_party/protobuf/src/google/protobuf/util/field_mask_util.h
diff --git a/third_party/protobuf/src/google/protobuf/util/field_mask_util.h b/third_party/protobuf/src/google/protobuf/util/field_mask_util.h
index 644161b940190735e6956c0cedbf1c3aff63c933..ab1f2e94c3a8e312790d92fccb5ba2088dfaf09f 100644
--- a/third_party/protobuf/src/google/protobuf/util/field_mask_util.h
+++ b/third_party/protobuf/src/google/protobuf/util/field_mask_util.h
@@ -28,6 +28,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Defines utilities for the FieldMask well known type.
+
 #ifndef GOOGLE_PROTOBUF_UTIL_FIELD_MASK_UTIL_H__
 #define GOOGLE_PROTOBUF_UTIL_FIELD_MASK_UTIL_H__
 
@@ -57,17 +59,26 @@ class LIBPROTOBUF_EXPORT FieldMaskUtil {
   static bool ToJsonString(const FieldMask& mask, string* out);
   static bool FromJsonString(StringPiece str, FieldMask* out);
 
+  // Get the descriptors of the fields which the given path from the message
+  // descriptor traverses, if field_descriptors is not null.
+  // Return false if the path is not valid, and the content of field_descriptors
+  // is unspecified.
+  static bool GetFieldDescriptors(
+      const Descriptor* descriptor, StringPiece path,
+      std::vector<const FieldDescriptor*>* field_descriptors);
+
   // Checks whether the given path is valid for type T.
   template <typename T>
   static bool IsValidPath(StringPiece path) {
-    return InternalIsValidPath(T::descriptor(), path);
+    return GetFieldDescriptors(T::descriptor(), path, NULL);
   }
 
   // Checks whether the given FieldMask is valid for type T.
   template <typename T>
   static bool IsValidFieldMask(const FieldMask& mask) {
     for (int i = 0; i < mask.paths_size(); ++i) {
-      if (!InternalIsValidPath(T::descriptor(), mask.paths(i))) return false;
+      if (!GetFieldDescriptors(T::descriptor(), mask.paths(i), NULL))
+        return false;
     }
     return true;
   }
@@ -107,10 +118,16 @@ class LIBPROTOBUF_EXPORT FieldMaskUtil {
   static bool IsPathInFieldMask(StringPiece path, const FieldMask& mask);
 
   class MergeOptions;
-  // Merges fields specified in a FieldMask into another message.
+  // Merges fields specified in a FieldMask into another message. See the
+  // comments in MergeOptions regarding compatibility with
+  // google/protobuf/field_mask.proto
   static void MergeMessageTo(const Message& source, const FieldMask& mask,
                              const MergeOptions& options, Message* destination);
 
+  // Removes from 'message' any field that is not represented in the given
+  // FieldMask. If the FieldMask is empty, does nothing.
+  static void TrimMessage(const FieldMask& mask, Message* message);
+
  private:
   friend class SnakeCaseCamelCaseTest;
   // Converts a field name from snake_case to camelCase:
@@ -141,13 +158,14 @@ class LIBPROTOBUF_EXPORT FieldMaskUtil {
   // successfully.
   static bool CamelCaseToSnakeCase(StringPiece input, string* output);
 
-  static bool InternalIsValidPath(const Descriptor* descriptor,
-                                  StringPiece path);
-
   static void InternalGetFieldMaskForAllFields(const Descriptor* descriptor,
                                                FieldMask* out);
 };
 
+// Note that for compatibility with the defined behaviour for FieldMask in
+// google/protobuf/field_mask.proto, set replace_message_fields and
+// replace_repeated_fields to 'true'. The default options are not compatible
+// with google/protobuf/field_mask.proto.
 class LIBPROTOBUF_EXPORT FieldMaskUtil::MergeOptions {
  public:
   MergeOptions()