Do not trigger Lo-Fi on main frame requests

components/data_reduction_proxy/content/browser/content_lofi_decider.cc

Index: components/data_reduction_proxy/content/browser/content_lofi_decider.cc
diff --git a/components/data_reduction_proxy/content/browser/content_lofi_decider.cc b/components/data_reduction_proxy/content/browser/content_lofi_decider.cc
index 12b323dc659fbd0e6744089fee207021599081dd..45f6220421b81a7337533d74ec02692f8f301f60 100644
--- a/components/data_reduction_proxy/content/browser/content_lofi_decider.cc
+++ b/components/data_reduction_proxy/content/browser/content_lofi_decider.cc
@@ -77,7 +77,8 @@ bool ContentLoFiDecider::MaybeAddLoFiDirectiveToHeaders(
       }
       header_value += chrome_proxy_lo_fi_preview_directive();
     }
-  } else {
+  } else if (!(request.load_flags() & net::LOAD_MAIN_FRAME)) {
+    // Do not add Lo-Fi header for main frame requests.
     header_value += chrome_proxy_lo_fi_directive();
   }