Remove the "Settings" packaged app

`enable_settings_app` was previously enabled for the app launcher on
non-chromeos platforms. But this hasn't been available on those
platforms for 1 milestone (since r394856), so it's time to purge the
associated code.

Note this is different to the ChromeOS Settings "App"
(chrome://flags/#enable-settings-window), and the arc / Android "App
Settings" App (arc:kSettingsAppId and b/28017599).

BUG=263236, 600915
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2121303003
Cr-Original-Commit-Position: refs/heads/master@{#404968}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 824bea8069b71ecb4f8c94fbeb78d19196304f1c

common.gypi

@@ -972,13 +972,6 @@
           'enable_print_preview%': 1,
         }],
 
-        # Do not enable the Settings App on ChromeOS.
-        ['enable_app_list==1 and chromeos==0', {
-          'enable_settings_app%': 1,
-        }, {
-          'enable_settings_app%': 0,
-        }],
-
         # Whether tests targets should be run, archived or just have the
         # dependencies verified. All the tests targets have the '_run' suffix,
         # e.g. base_unittests_run runs the target base_unittests. The test
@@ -1244,7 +1237,6 @@
     'create_standalone_apk%': 1,
     'enable_app_list%': '<(enable_app_list)',
     'use_default_render_theme%': '<(use_default_render_theme)',
-    'enable_settings_app%': '<(enable_settings_app)',
     'google_api_key%': '<(google_api_key)',
     'google_default_client_id%': '<(google_default_client_id)',
     'google_default_client_secret%': '<(google_default_client_secret)',
@@ -2166,9 +2158,6 @@
       ['enable_app_list==1', {
         'grit_defines': ['-D', 'enable_app_list'],
       }],
-      ['enable_settings_app==1', {
-        'grit_defines': ['-D', 'enable_settings_app'],
-      }],
       ['use_concatenated_impulse_responses==1', {
         'grit_defines': ['-D', 'use_concatenated_impulse_responses'],
       }],
@@ -2950,9 +2939,6 @@
       ['enable_app_list==1', {
         'defines': ['ENABLE_APP_LIST=1'],
       }],
-      ['enable_settings_app==1', {
-        'defines': ['ENABLE_SETTINGS_APP=1'],
-      }],
       ['disable_file_support==1', {
         'defines': ['DISABLE_FILE_SUPPORT=1'],
       }],

config/BUILD.gn

@@ -201,9 +201,6 @@ config("feature_flags") {
   if (enable_app_list) {
     defines += [ "ENABLE_APP_LIST=1" ]
   }
-  if (enable_settings_app) {
-    defines += [ "ENABLE_SETTINGS_APP=1" ]
-  }
   if (enable_supervised_users) {
     defines += [ "ENABLE_SUPERVISED_USERS=1" ]
   }

config/features.gni

@@ -155,8 +155,6 @@ enable_themes = !is_android && !is_ios
 enable_rlz_support = is_win || is_mac || is_ios || is_chromeos
 enable_rlz = is_chrome_branded && enable_rlz_support
 
-enable_settings_app = enable_app_list && !is_chromeos
-
 enable_service_discovery = enable_mdns || is_mac
 
 # Image loader extension is enabled on ChromeOS only.