XXS: Update a comment in the safebrowsing.proto file

components/safe_browsing_db/safebrowsing.proto

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // This file includes Safe Browsing V4 API blacklist request and response
 // protocol buffers. They should be kept in sync with the server implementation.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
@@ skipping 131 matching lines @@
 
     // The type of response. This may indicate that an action is required by the
     // client when the response is received.
     optional ResponseType response_type = 4;
 
     // A set of entries to add to a local threat type's list. Repeated to allow
     // for a combination of compressed and raw data to be sent in a single
     // response.
     repeated ThreatEntrySet additions = 5;
 
-    // A set of entries to remove from a local threat type's list. Repeated for
-    // the same reason as above.
+    // A set of entries to remove from a local threat type's list. In practice,
+    // this field is empty or contains exactly one ThreatEntrySet.
     repeated ThreatEntrySet removals = 6;
 
     // The new client state, in encrypted format. Opaque to clients.
     optional bytes new_client_state = 7;
 
     // The expected SHA256 hash of the client state; that is, of the sorted list
     // of all hashes present in the database after applying the provided update.
     // If the client state doesn't match the expected state, the client must
     // disregard this update and retry later.
     optional Checksum checksum = 8;
@@ skipping 300 matching lines @@
   optional int64 seconds = 1;
 
   // Signed fractions of a second at nanosecond resolution of the span
   // of time. Durations less than one second are represented with a 0
   // `seconds` field and a positive or negative `nanos` field. For durations
   // of one second or more, a non-zero value for the `nanos` field must be
   // of the same sign as the `seconds` field. Must be from -999,999,999
   // to +999,999,999 inclusive.
   optional int32 nanos = 2;
 }