Restrict transmission of external exp ids to signed in users.

components/variations/net/variations_http_headers.cc

Index: components/variations/net/variations_http_headers.cc
diff --git a/components/variations/net/variations_http_headers.cc b/components/variations/net/variations_http_headers.cc
index 48e84eb190c96f0f8d1ea955ddda215676d9d206..32179745d559cab9380b261a36be6ee8694d9b2e 100644
--- a/components/variations/net/variations_http_headers.cc
+++ b/components/variations/net/variations_http_headers.cc
@@ -44,6 +44,7 @@ const char kClientData[] = "X-Client-Data";
 void AppendVariationHeaders(const GURL& url,
                             bool incognito,
                             bool uma_enabled,
+                            bool is_signed_in,
                             net::HttpRequestHeaders* headers) {
   // Note the criteria for attaching client experiment headers:
   // 1. We only transmit to Google owned domains which can evaluate experiments.
@@ -62,7 +63,8 @@ void AppendVariationHeaders(const GURL& url,
     headers->SetHeaderIfMissing(kChromeUMAEnabled, "1");
 
   const std::string variation_ids_header =
-      VariationsHttpHeaderProvider::GetInstance()->GetClientDataHeader();
+      VariationsHttpHeaderProvider::GetInstance()->GetClientDataHeader(
+          is_signed_in);
   if (!variation_ids_header.empty()) {
     // Note that prior to M33 this header was named X-Chrome-Variations.
     headers->SetHeaderIfMissing(kClientData, variation_ids_header);