[rulebased] Don't use NativeInputMethodEngine when rulebased flag is off.

As a precaution, use the old InputMethodEngine when rulebased flag is
off so that we return to old behaviour if we had to turn off the flag
due to bugs.

Bug: 1034355
Change-Id: I9a2b5288b0ca4f56d5c9972374720dc2318c3b14
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2026547
Commit-Queue: Leo Zhang <googleo@chromium.org>
Reviewed-by: Leo Zhang <googleo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736161}

chrome/browser/extensions/api/input_ime/input_ime_api_chromeos.cc

@@ -22,6 +22,7 @@
 #include "chrome/browser/ui/ash/keyboard/chrome_keyboard_controller_client.h"
 #include "chrome/common/extensions/api/input_ime.h"
 #include "chrome/common/extensions/api/input_method_private.h"
+#include "chromeos/constants/chromeos_features.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/process_manager.h"
 #include "extensions/common/manifest_handlers/background_info.h"
@@ -462,9 +463,11 @@ bool InputImeEventRouter::RegisterImeExtension(
   }
 
   auto observer = std::make_unique<ImeObserverChromeOS>(extension_id, profile);
-  auto engine = (extension_id == "jkghodnilhceideoidjikpgommlajknk")
-                    ? std::make_unique<chromeos::NativeInputMethodEngine>()
-                    : std::make_unique<chromeos::InputMethodEngine>();
+  auto engine =
+      (extension_id == "jkghodnilhceideoidjikpgommlajknk" &&
+       base::FeatureList::IsEnabled(chromeos::features::kNativeRuleBasedTyping))
+          ? std::make_unique<chromeos::NativeInputMethodEngine>()
+          : std::make_unique<chromeos::InputMethodEngine>();
   engine->Initialize(std::move(observer), extension_id.c_str(), profile);
   engine_map_[extension_id] = std::move(engine);