Fix typo in proto comment

Change-Id: I41a7558c411870a106a7f5766f68c91a136ad579
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1645354Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Commit-Queue: Jit Yao Yap <jityao@google.com>
Cr-Commit-Position: refs/heads/master@{#666261}

components/policy/proto/device_management_backend.proto

@@ -1930,7 +1930,7 @@ message DeviceRemoteCommandResponse {
   // (and vice versa).
   //
   // The secure_commands.data field contains a serialized
-  // RemoteCommand. The  ecure_commands.signature field is a
+  // RemoteCommand. The secure_commands.signature field is a
   // signature of the data field with the policy key for the
   // domain the device belongs to.
   repeated SignedData secure_commands = 2;