Fix IsCros1pKorean() to properly distinguish Chrome OS vs Chromium OS.

This is meant for b/302255943, so intended to only return "true"
when it's 1P Korean input method on (Google-flavoured) Chrome OS
(i.e. not 3P, not even 1P but open-source Chromium OS). It was
an oversight to miss out the Chrome OS preprocessor guards. This
will soon be used for b/298907146 with the exact same intention.

CQ_INCLUDE_TRYBOTS=luci.chrome.try:chromeos-betty-pi-arc-chrome

Bug: b/302255943, b/298907146
Change-Id: I41f98b9332cadf6e3015f8cfbcc08da4a3facbb6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5075905
Reviewed-by: Darren Shen <shend@chromium.org>
Commit-Queue: Bao-Duy Tran <tranbaoduy@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1232558}

ui/base/ime/ash/extension_ime_util.cc

@@ -179,8 +179,17 @@ bool IsExperimentalMultilingual(const std::string& input_method_id) {
 }
 
 bool IsCros1pKorean(const std::string& input_method_id) {
+  // TODO(crbug.com/1162211): Input method IDs are tuples of extension type,
+  // extension ID, and extension-local input method ID. However, currently
+  // they're just concats of the three constituent pieces of info, hence StrCat
+  // here. Replace StrCat once they're no longer unstructured string concats.
+
+#if BUILDFLAG(GOOGLE_CHROME_BRANDING)
   return input_method_id == base::StrCat({kComponentExtensionIMEPrefix,
                                           kXkbExtensionId, "ko-t-i0-und"});
+#else
+  return false;
+#endif
 }
 
 }  // namespace extension_ime_util

ui/base/ime/ash/extension_ime_util_unittest.cc

@@ -110,4 +110,30 @@ TEST(ExtensionIMEUtilTest, IsExperimentalMultilingualTest) {
                         "experimental_hello_world"})));
 }
 
+TEST(ExtensionIMEUtilTest, IsCros1pKoreanTest) {
+  // TODO(crbug.com/1162211): Input method IDs are tuples of extension type,
+  // extension ID, and extension-local input method ID. However, currently
+  // they're just concats of the three constituent pieces of info, hence StrCat
+  // here. Replace StrCat once they're no longer unstructured string concats.
+
+  EXPECT_FALSE(extension_ime_util::IsCros1pKorean(
+      base::StrCat({"some_extension_type", "some_extension_id",
+                    "some_local_input_method_id"})));
+
+  EXPECT_FALSE(extension_ime_util::IsCros1pKorean(base::StrCat(
+      {"_comp_ime_", "some_extension_id", "some_local_input_method_id"})));
+
+  EXPECT_FALSE(extension_ime_util::IsCros1pKorean(
+      base::StrCat({"_comp_ime_", "jkghodnilhceideoidjikpgommlajknk",
+                    "some_local_input_method_id"})));
+
+#if BUILDFLAG(GOOGLE_CHROME_BRANDING)
+  EXPECT_TRUE(
+#else
+  EXPECT_FALSE(
+#endif
+      extension_ime_util::IsCros1pKorean(base::StrCat(
+          {"_comp_ime_", "jkghodnilhceideoidjikpgommlajknk", "ko-t-i0-und"})));
+}
+
 }  // namespace ash