Update some comments about variations headers API use.

Based on post-review comments on:
https://codereview.chromium.org/2558913003/

BUG=none
TBR=mattm@chromium.org,donnd@chromium.org,afakhry@chromium.org,noyau@chromium.org

Review-Url: https://codereview.chromium.org/2627033003
Cr-Commit-Position: refs/heads/master@{#443250}

chrome/browser/android/contextualsearch/contextual_search_delegate.cc

@@ -136,8 +136,8 @@ void ContextualSearchDelegate::ContinueSearchTermResolutionRequest() {
 
   // 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(
       search_term_fetcher_->GetOriginalURL(),

chrome/browser/safe_browsing/srt_fetcher_win.cc

@@ -632,8 +632,8 @@ class SRTFetcher : public net::URLFetcherDelegate {
     ProfileIOData* io_data = ProfileIOData::FromResourceContext(
         profile_->GetResourceContext());
     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(
         url_fetcher_->GetOriginalURL(), io_data->IsOffTheRecord(),

components/autofill/core/browser/autofill_download_manager.cc

@@ -247,8 +247,8 @@ bool AutofillDownloadManager::StartRequest(
                         net::LOAD_DO_NOT_SEND_COOKIES);
   // 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(fetcher->GetOriginalURL(),
                                      driver_->IsOffTheRecord(), false,

components/feedback/feedback_uploader_chrome.cc

@@ -60,8 +60,8 @@ void FeedbackUploaderChrome::DispatchReport(const std::string& data) {
       fetcher, data_use_measurement::DataUseUserData::FEEDBACK_UPLOADER);
   // Tell feedback server about the variation state of this install.
   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(fetcher->GetOriginalURL(),
                                      context_->IsOffTheRecord(), false,

components/ntp_snippets/remote/ntp_snippets_json_request.cc

@@ -356,8 +356,8 @@ std::string NTPSnippetsJsonRequest::Builder::BuildHeaders() const {
     headers.SetHeader("Authorization", auth_header_);
   }
   // Add X-Client-Data header with experiment IDs from field trials.
-  // 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(url_,
                                      false,  // incognito

components/omnibox/browser/search_provider.cc

@@ -890,8 +890,8 @@ std::unique_ptr<net::URLFetcher> SearchProvider::CreateSuggestFetcher(
   fetcher->SetLoadFlags(net::LOAD_DO_NOT_SAVE_COOKIES);
   // 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(fetcher->GetOriginalURL(),
                                      client()->IsOffTheRecord(), false,

components/omnibox/browser/zero_suggest_provider.cc

@@ -333,8 +333,8 @@ void ZeroSuggestProvider::Run(const GURL& suggest_url) {
     fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SAVE_COOKIES);
     // 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(fetcher_->GetOriginalURL(),
                                        client()->IsOffTheRecord(), false,

components/suggestions/suggestions_service_impl.cc

@@ -423,8 +423,8 @@ SuggestionsServiceImpl::CreateSuggestionsRequest(
   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);

ios/chrome/browser/ui/contextual_search/contextual_search_delegate.cc

@@ -173,8 +173,8 @@ void ContextualSearchDelegate::RequestServerSearchTerm() {
 
   // 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(search_term_fetcher_->GetOriginalURL(),
                                      browser_state_->IsOffTheRecord(), false,