Use the fake language for ARC IMEs

With this, such IMEs will be excluded from the available IME list
for English.

BUG=b:74499980
TEST=unit_tests

Change-Id: Ied09c0c787bf54527229133a1d792cabbc4aac7c
Reviewed-on: https://chromium-review.googlesource.com/1113206Reviewed-by: Yuichiro Hanada <yhanada@chromium.org>
Commit-Queue: Yusuke Sato <yusukes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569992}

chrome/browser/chromeos/arc/input_method_manager/arc_input_method_manager_service.cc

@@ -209,10 +209,15 @@ void ArcInputMethodManagerService::SwitchImeTo(const std::string& ime_id) {
 chromeos::input_method::InputMethodDescriptor
 ArcInputMethodManagerService::BuildInputMethodDescriptor(
     const mojom::ImeInfo* info) {
-  // TODO(yhanada): Set the special layout/language value for ARC IMEs after
-  // making settings and IME menu tray support it.
-  std::vector<std::string> layouts{"us"};
-  std::vector<std::string> languages{"en-US"};
+  // We don't care too much about |layouts| at this point since the feature is
+  // for tablet mode.
+  const std::vector<std::string> layouts{"us"};
+
+  // Set the fake language so that the IME is shown in the special section in
+  // chrome://settings.
+  const std::vector<std::string> languages{
+      chromeos::extension_ime_util::kArcImeLanguage};
+
   const std::string display_name = info->display_name;
 
   const std::string& input_method_id =

chrome/browser/chromeos/arc/input_method_manager/arc_input_method_manager_service_unittest.cc

@@ -320,6 +320,9 @@ TEST_F(ArcInputMethodManagerServiceTest, OnImeInfoChanged) {
     EXPECT_EQ(android_ime_id1, GetComponentIDByInputMethodID(
                                    std::get<1>(added_extensions[0])[0].id()));
     EXPECT_EQ(display_name1, std::get<1>(added_extensions[0])[0].name());
+    ASSERT_EQ(1u, std::get<1>(added_extensions[0])[0].language_codes().size());
+    EXPECT_TRUE(chromeos::extension_ime_util::IsLanguageForArcIME(
+        (std::get<1>(added_extensions[0])[0].language_codes())[0]));
 
     // Emulate enabling ARC IME from chrome://settings.
     const std::string& arc_ime_id = std::get<1>(added_extensions[0])[0].id();