Update some comments about variations headers API use.

components/suggestions/suggestions_service_impl.cc

 // Copyright 2014 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.
 
 #include "components/suggestions/suggestions_service_impl.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/feature_list.h"
@@ skipping 405 matching lines @@
       net::URLFetcher::Create(0, url, net::URLFetcher::GET, this);
   data_use_measurement::DataUseUserData::AttachToFetcher(
       request.get(), data_use_measurement::DataUseUserData::SUGGESTIONS);
   int load_flags = net::LOAD_DISABLE_CACHE | net::LOAD_DO_NOT_SEND_COOKIES |
                    net::LOAD_DO_NOT_SAVE_COOKIES;
 
   request->SetLoadFlags(load_flags);
   request->SetRequestContext(url_request_context_);
   // Add Chrome experiment state to the request headers.
   net::HttpRequestHeaders headers;
-  // Note: It's fine to pass in |is_signed_in| false, which does not affect
-  // transmission of experiment ids coming from the variations server.
+  // Note: It's OK to pass |is_signed_in| false if it's unknown, as it does
+  // not affect transmission of experiments coming from the variations server.
   bool is_signed_in = false;
   variations::AppendVariationHeaders(request->GetOriginalURL(), false, false,
                                      is_signed_in, &headers);
   request->SetExtraRequestHeaders(headers.ToString());
   if (!access_token.empty()) {
     request->AddExtraRequestHeader(
         base::StringPrintf(kAuthorizationHeaderFormat, access_token.c_str()));
   }
   return request;
 }
@@ skipping 120 matching lines @@
     scheduling_delay_ = TimeDelta::FromSeconds(kDefaultSchedulingDelaySec);
   } else {
     TimeDelta candidate_delay =
         scheduling_delay_ * kSchedulingBackoffMultiplier;
     if (candidate_delay < TimeDelta::FromSeconds(kSchedulingMaxDelaySec))
       scheduling_delay_ = candidate_delay;
   }
 }
 
 }  // namespace suggestions