Refactor FlutterTizenEngine a bit

Author: swift-kim

shell/platform/tizen/channels/localization_channel.h

@@ -21,4 +21,5 @@ class LocalizationChannel {
 
   FLUTTER_API_SYMBOL(FlutterEngine) flutter_engine_;
 };
+
 #endif  // EMBEDDER_LOCALIZATION_CHANNEL_H_

shell/platform/tizen/channels/text_input_channel.cc

@@ -223,7 +223,7 @@ TextInputChannel::TextInputChannel(flutter::BinaryMessenger* messenger,
   }
   if (imf_context_) {
     ecore_imf_context_client_window_set(
-        imf_context_, (void*)engine_->tizen_renderer->GetWindowId());
+        imf_context_, (void*)engine_->renderer->GetWindowId());
     RegisterIMFCallback();
   } else {
     FT_LOGE("Failed to create imfContext");

shell/platform/tizen/flutter_tizen.cc

@@ -58,12 +58,12 @@ FlutterDesktopPluginRegistrarRef FlutterDesktopGetPluginRegistrar(
 
 FlutterDesktopMessengerRef FlutterDesktopEngineGetMessenger(
     FlutterDesktopEngineRef engine) {
-  return EngineFromHandle(engine)->messenger();
+  return EngineFromHandle(engine)->messenger.get();
 }
 
 FlutterDesktopMessengerRef FlutterDesktopPluginRegistrarGetMessenger(
     FlutterDesktopPluginRegistrarRef registrar) {
-  return registrar->engine->messenger();
+  return registrar->engine->messenger.get();
 }
 
 void FlutterDesktopPluginRegistrarSetDestructionHandler(
@@ -132,23 +132,23 @@ void FlutterDesktopMessengerSetCallback(FlutterDesktopMessengerRef messenger,
 }
 
 void FlutterDesktopNotifyLocaleChange(FlutterDesktopEngineRef engine) {
-  EngineFromHandle(engine)->SendLocales();
+  EngineFromHandle(engine)->localization_channel->SendLocales();
 }
 
 void FlutterDesktopNotifyAppIsInactive(FlutterDesktopEngineRef engine) {
-  EngineFromHandle(engine)->AppIsInactive();
+  EngineFromHandle(engine)->lifecycle_channel->AppIsInactive();
 }
 
 void FlutterDesktopNotifyAppIsResumed(FlutterDesktopEngineRef engine) {
-  EngineFromHandle(engine)->AppIsResumed();
+  EngineFromHandle(engine)->lifecycle_channel->AppIsResumed();
 }
 
 void FlutterDesktopNotifyAppIsPaused(FlutterDesktopEngineRef engine) {
-  EngineFromHandle(engine)->AppIsPaused();
+  EngineFromHandle(engine)->lifecycle_channel->AppIsPaused();
 }
 
 void FlutterDesktopNotifyAppIsDetached(FlutterDesktopEngineRef engine) {
-  EngineFromHandle(engine)->AppIsDetached();
+  EngineFromHandle(engine)->lifecycle_channel->AppIsDetached();
 }
 
 void FlutterDesktopNotifyLowMemoryWarning(FlutterDesktopEngineRef engine) {