Restrict transmission of external exp ids to signed in users.

components/variations/net/variations_http_headers.h

Index: components/variations/net/variations_http_headers.h
diff --git a/components/variations/net/variations_http_headers.h b/components/variations/net/variations_http_headers.h
index d6280e56e8e0584e4cdad1a803ca7a38e46b88b7..fe4d597e7363ec8b06f4b8d7a8a9a0b937677370 100644
--- a/components/variations/net/variations_http_headers.h
+++ b/components/variations/net/variations_http_headers.h
@@ -17,12 +17,16 @@ class GURL;
 namespace variations {
 
 // Adds Chrome experiment and metrics state as custom headers to |headers|.
-// Some headers may not be set given the |incognito| mode or whether
-// the user has |uma_enabled|.  Also, we never transmit headers to non-Google
-// sites, which is checked based on the destination |url|.
+// The content of the headers will depend on |incognito|, |uma_enabled| and
+// |is_signed_in| parameters. It is fine to pass false for |is_signed_in| if the
+// state is not known to the caller. This will prevent addition of ids of type
+// GOOGLE_WEB_PROPERTIES_SIGNED_IN, which is not the case for any ids that come
+// from the variations server. These headers are never transmitted to non-Google
+// web sites, which is checked based on the destination |url|.
 void AppendVariationHeaders(const GURL& url,
                             bool incognito,
                             bool uma_enabled,
+                            bool is_signed_in,
                             net::HttpRequestHeaders* headers);
 
 // Returns the HTTP header names which are added by AppendVariationHeaders().