Adding UMA on page load size for pages with Media

chrome/test/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
@@ skipping 3229 matching lines @@
     "../browser/ntp_snippets/bookmark_last_visit_updater_unittest.cc",
     "../browser/ntp_snippets/download_suggestions_provider_unittest.cc",
     "../browser/page_load_metrics/metrics_web_contents_observer_unittest.cc",
     "../browser/page_load_metrics/observers/aborts_page_load_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/amp_page_load_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/data_reduction_proxy_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/document_write_page_load_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/from_gws_page_load_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/google_captcha_observer_unittest.cc",
+    "../browser/page_load_metrics/observers/media_page_load_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.cc",
     "../browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.h",
     "../browser/page_load_metrics/observers/previews_page_load_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/protocol_page_load_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/service_worker_page_load_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/subresource_filter_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/tab_restore_page_load_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/observers/ukm_page_load_metrics_observer_unittest.cc",
     "../browser/page_load_metrics/user_input_tracker_unittest.cc",
@@ skipping 1923 matching lines @@
 }
 
 if (is_win) {
   loadable_module("conflicts_dll") {
     testonly = true
     sources = [
       "conflicts/conflicts_dll.cc",
     ]
   }
 }