Lo-Fi snackbar should only be shown for the first q=low response of a page

components/data_reduction_proxy/content/browser/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 source_set("browser") {
   sources = [
     "content_lofi_decider.cc",
     "content_lofi_decider.h",
+    "content_lofi_ui_service.cc",
+    "content_lofi_ui_service.h",
     "data_reduction_proxy_message_filter.cc",
     "data_reduction_proxy_message_filter.h",
   ]
 
   deps = [
     "//base",
     "//components/data_reduction_proxy/content/common",
     "//components/data_reduction_proxy/core/browser",
     "//components/data_reduction_proxy/core/common",
     "//content/public/browser",
@@ skipping 20 matching lines @@
       "//skia",
       "//ui/base",
     ]
   }
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "content_lofi_decider_unittest.cc",
+    "content_lofi_ui_service_unittest.cc",
     "data_reduction_proxy_message_filter_unittest.cc",
   ]
 
   deps = [
     ":browser",
     "//base",
     "//components/data_reduction_proxy/core/browser:test_support",
     "//components/data_reduction_proxy/core/common:test_support",
     "//content/public/browser",
     "//content/public/common",
     "//content/test:test_support",
     "//net:test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 
   if (is_android) {
     sources += [
       "data_reduction_proxy_debug_blocking_page_unittest.cc",
       "data_reduction_proxy_debug_resource_throttle_unittest.cc",
       "data_reduction_proxy_debug_ui_manager_unittest.cc",
     ]
 
     deps += [
       "//mojo/public/cpp/bindings",
       "//skia",
     ]
   }
 }