Add ScopedMacRTL class for Cocoa browser RTL testing

ui/base/BUILD.gn

Index: ui/base/BUILD.gn
diff --git a/ui/base/BUILD.gn b/ui/base/BUILD.gn
index cbb826e348fd1a69dbd43d26cb1de69128ac03c3..462d4b9ad4455e694110f402439440e1270f1357 100644
--- a/ui/base/BUILD.gn
+++ b/ui/base/BUILD.gn
@@ -126,6 +126,8 @@ component("base") {
     "cocoa/nsview_additions.mm",
     "cocoa/remote_layer_api.h",
     "cocoa/remote_layer_api.mm",
+    "cocoa/rtl_feature.h",
+    "cocoa/rtl_feature.mm",
     "cocoa/scoped_cg_context_smooth_fonts.h",
     "cocoa/scoped_cg_context_smooth_fonts.mm",
     "cocoa/three_part_image.h",
@@ -657,12 +659,6 @@ static_library("test_support") {
     ]
   }
 
-  if (is_mac) {
-    sources += [ "test/user_interactive_test_case_mac.mm" ]
-  } else {
-    sources += [ "test/user_interactive_test_case.cc" ]
-  }
-
   public_deps = [
     ":base",
   ]
@@ -678,6 +674,21 @@ static_library("test_support") {
     "//ui/gfx/geometry",
   ]
 
+  if (is_mac) {
+    sources += [
+      "test/scoped_mac_rtl.h",
+      "test/scoped_mac_rtl.mm",

[tapted, 2016/12/07 23:20:27]

(maybe it's historical but..) the current convention is to list files in the
main `sources = [` list "if that works". I think this will, since it is .mm, but
the _mac should be at the end anyways (see next comment), which will make it
even more workier.  (the deps below should stay here, however)

Edit: maybe it's here because of iOS -- see comment in scoped_mac_rtl.h

+      "test/user_interactive_test_case_mac.mm",
+    ]
+
+    deps += [
+      "//base:i18n",
+      "//base/test:test_support",
+    ]
+  } else {
+    sources += [ "test/user_interactive_test_case.cc" ]
+  }
+
   if (build_ime) {
     sources += [
       "ime/dummy_input_method.cc",