Removing deprecated ios/web/user_metrics.cc and references to it.

ios/web/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("//ios/web/js_compile.gni")
 import("//testing/test.gni")
 import("//tools/grit/grit_rule.gni")
 
 source_set("web") {
   deps = [
@@ skipping 106 matching lines @@
     "public/referrer_util.h",
     "public/security_style.h",
     "public/ssl_status.cc",
     "public/ssl_status.h",
     "public/string_util.h",
     "public/url_data_source_ios.h",
     "public/url_scheme_util.h",
     "public/url_schemes.h",
     "public/url_schemes.mm",
     "public/url_util.h",
-    "public/user_metrics.h",
     "public/web_capabilities.cc",
     "public/web_capabilities.h",
     "public/web_client.h",
     "public/web_client.mm",
     "public/web_kit_constants.h",
     "public/web_state/context_menu_params.h",
     "public/web_state/credential.h",
     "public/web_state/crw_web_controller_observer.h",
     "public/web_state/crw_web_user_interface_delegate.h",
     "public/web_state/crw_web_view_proxy.h",
@@ skipping 19 matching lines @@
     "public/web_state/web_state_observer_bridge.h",
     "public/web_state/web_state_policy_decider.h",
     "public/web_state/web_state_user_data.h",
     "public/web_thread.h",
     "public/web_thread_delegate.h",
     "public/web_ui_ios_data_source.h",
     "public/web_view_creation_util.h",
     "string_util.cc",
     "url_scheme_util.mm",
     "url_util.cc",
-    "user_metrics.cc",
     "web_kit_constants.cc",
     "web_state/blocked_popup_info.h",
     "web_state/blocked_popup_info.mm",
     "web_state/context_menu_params.mm",
     "web_state/credential.cc",
     "web_state/crw_pass_kit_downloader.h",
     "web_state/crw_pass_kit_downloader.mm",
     "web_state/crw_web_view_proxy_impl.h",
     "web_state/crw_web_view_proxy_impl.mm",
     "web_state/crw_web_view_scroll_view_proxy.mm",
@@ skipping 353 matching lines @@
   use_qualified_include = true
   outputs = [
     "grit/ios_web_resources.h",
     "ios_web_resources.pak",
   ]
   grit_flags = [
     "-E",
     "root_out_dir=" + rebase_path(root_out_dir, root_build_dir),
   ]
 }