Switch variations http headers to only be reported over https.

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..0a4b29a2b8bf22cc81b15a8b11e5a74d74c99243 100644
--- a/components/variations/net/variations_http_headers.h
+++ b/components/variations/net/variations_http_headers.h
@@ -31,7 +31,8 @@ std::set<std::string> GetVariationHeaderNames();
 namespace internal {
 
 // Checks whether variation headers should be appended to requests to the
-// specified |url|. Returns true for google.<TLD> and youtube.<TLD> URLs.
+// specified |url|. Returns true for google.<TLD> and youtube.<TLD> URLs with
+// the https scheme.
 bool ShouldAppendVariationHeaders(const GURL& url);
 
 }  // namespace internal