Simplify test locales in Mac's ui_unittests Framework

Mac creates a mini-framework in `ui_unittests Framework` so that ui
tests can get a resource bundle without depending on the Chrome
framework.

The way it generated locale information was causing build flakes since
two instances of repack_locales.py could be writing to
out/../gen/repack. Tests always use en-US, so instead just do what iOS
does and copy ui_test.pak to en.lproj/locale.pak and roll it into the
mini-framework bundle.

BUG=410468

Review URL: https://codereview.chromium.org/552963002

Cr-Commit-Position: refs/heads/master@{#294052}

ui/base/ui_base_tests_bundle.gypi

@@ -7,8 +7,6 @@
 {
   'product_name': 'ui_unittests Framework',
   'variables': {
-    'grit_out_dir': '<(SHARED_INTERMEDIATE_DIR)/ui',
-
     # There is no executable in the mock framework, and so nothing to strip.
     'mac_strip': 0,
   },
@@ -25,7 +23,10 @@
   'mac_bundle_resources': [
     'test/framework-Info.plist',
     '<(PRODUCT_DIR)/ui_test.pak',
-    '<!@pymod_do_main(repack_locales -o -p <(OS) -g <(grit_out_dir) -s <(SHARED_INTERMEDIATE_DIR) -x <(SHARED_INTERMEDIATE_DIR) <(locales))',
+
+    # Just include the English-US locale made by ui_resources.gyp:ui_test_pak.
+    # Note that the file is just a copy of ui_test.pak, with a different path.
+    '<(PRODUCT_DIR)/ui/en.lproj/locale.pak',
   ],
   'mac_bundle_resources!': [
     'test/framework-Info.plist',

ui/resources/BUILD.gn

@@ -52,12 +52,12 @@ if (!is_mac) {
   }
 }
 
-# On iOS the output needs to additionally be copied to another location, so
-# we have this intermediate step.
+# On iOS and Mac the output needs to additionally be copied to another location,
+# so we have this intermediate step.
 #
 # GYP version: ui/resources/ui_resources.gyp:ui_test_pak
 #              (copy_ui_test_pak action)
-if (is_ios) {
+if (is_ios || is_mac) {
   copy("ui_test_pak") {
     sources = [ "$root_out_dir/ui_test.pak" ]
     outputs = [ "$root_out_dir/ui/en.lproj/locale.pak" ]
@@ -74,7 +74,7 @@ repack("repack_ui_test_pak") {
   # Depend on ui_test_pak instead of this one.
   visibility = [ ":ui_test_pak" ]
 
-  sources = [ 
+  sources = [
     "$root_gen_dir/ui/resources/ui_resources_100_percent.pak",
     "$root_gen_dir/ui/resources/webui_resources.pak",
     "$root_gen_dir/ui/strings/app_locale_settings_en-US.pak",

ui/resources/ui_resources.gyp

@@ -74,7 +74,7 @@
             },
           ],
         }],
-        ['OS == "ios"', {
+        ['OS == "ios" or OS == "mac"', {
           'actions': [
             {
               # GN version: //ui/resources:copy_ui_test_pak