Synchronize new proto changes.
diff --git a/google/devtools/remoteexecution/v1test/remote_execution.proto b/google/devtools/remoteexecution/v1test/remote_execution.proto
index fbac332..454962a 100644
--- a/google/devtools/remoteexecution/v1test/remote_execution.proto
+++ b/google/devtools/remoteexecution/v1test/remote_execution.proto
@@ -574,15 +574,9 @@
 
   // The output directories of the action. For each output directory requested,
   // if the corresponding directory existed after the action completed, a single
-  // entry will be present in the output list. The client can retrieve the full
-  // [Directory][google.devtools.remoteexecution.v1test.Directory] structure
-  // using
-  // [ContentAddressableStorage.GetTree][google.devtools.remoteexecution.v1test.ContentAddressableStorage.GetTree].
-  //
-  // If the action does not produce the requested output, or produces a
-  // directory where a regular file is expected or vice versa, then that output
-  // will be omitted from the list. The server is free to arrange the output
-  // list as desired; clients MUST NOT assume that the output list is sorted.
+  // entry will be present in the output list, which will contain the digest of
+  // a [Tree][google.devtools.remoteexecution.v1.test.Tree] message containing
+  // the directory tree.
   repeated OutputDirectory output_directories = 3;
 
   // The exit code of the command.
@@ -647,7 +641,6 @@
   bool is_executable = 4;
 }
 
-
 // A `Tree` contains all the
 // [Directory][google.devtools.remoteexecution.v1test.Directory] protos in a
 // single directory Merkle tree, compressed into one message.
@@ -939,10 +932,12 @@
   string tool_version = 2;
 }
 
-// An optional Metadata to attach to a RPC request to tell the server about an
-// external context of the request.
-// If used, the header name should be remote-request-metadata-bin and the
-// contents the base64 encoded binary RequestMetadata message.
+// An optional Metadata to attach to any RPC request to tell the server about an
+// external context of the request. The server may use this for logging or other
+// purposes. To use it, the client attaches the header to the call using the
+// canonical proto serialization:
+// name: google.devtools.remoteexecution.v1test.requestmetadata-bin
+// contents: the base64 encoded binary RequestMetadata message.
 message RequestMetadata {
   // The details for the tool invoking the requests.
   ToolDetails tool_details = 1;