Flush UKM metrics when backgrounded on Android and iOS.

ios/chrome/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.
 
 import("//build/buildflag_header.gni")
 import("//build/config/features.gni")
 import("//build/config/ios/rules.gni")
 import("//rlz/features/features.gni")
 import("//third_party/protobuf/proto_library.gni")
 
@@ skipping 129 matching lines @@
     "//components/language_usage_metrics",
     "//components/metrics:profiler_ios",
     "//components/metrics_services_manager",
     "//components/net_log",
     "//components/network_time",
     "//components/open_from_clipboard",
     "//components/physical_web/data_source",
     "//components/prefs",
     "//components/rappor",
     "//components/translate/core/browser",
+    "//components/ukm",
     "//components/update_client",
     "//components/variations",
     "//components/variations/field_trial_config",
     "//components/variations/service",
     "//ios/chrome/browser/browser_state",
     "//ios/chrome/browser/browser_state:browser_state_impl",
     "//ios/chrome/browser/component_updater",
     "//ios/chrome/browser/first_run",
     "//ios/chrome/browser/history",
     "//ios/chrome/browser/metrics",
@@ skipping 62 matching lines @@
 
 source_set("browser_internal") {
   sources = [
     "callback_counter.h",
     "callback_counter.mm",
   ]
   deps = [
     "//base",
   ]
 }