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 fe4d597e7363ec8b06f4b8d7a8a9a0b937677370..f91c3eaf7cdd17457448958d9dbff409ba2c5a21 100644
--- a/components/variations/net/variations_http_headers.h
+++ b/components/variations/net/variations_http_headers.h
@@ -35,7 +35,8 @@ 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