Remove unused onStartChatClick callback from WelcomeScreen (#199)

Author: kirklandsign

llm/android/LlamaDemo/app/src/main/java/com/example/executorchllamademo/WelcomeActivity.kt

@@ -56,9 +56,6 @@ class WelcomeActivity : ComponentActivity() {
                         },
                         onAppSettingsClick = {
                             startActivity(Intent(this@WelcomeActivity, AppSettingsActivity::class.java))
-                        },
-                        onStartChatClick = {
-                            startActivity(Intent(this@WelcomeActivity, MainActivity::class.java))
                         }
                     )
                 }

llm/android/LlamaDemo/app/src/main/java/com/example/executorchllamademo/ui/screens/WelcomeScreen.kt

@@ -43,8 +43,7 @@ import com.example.executorchllamademo.ui.theme.LocalAppColors
 fun WelcomeScreen(
     onLoadModelClick: () -> Unit = {},
     onDownloadModelClick: () -> Unit = {},
-    onAppSettingsClick: () -> Unit = {},
-    onStartChatClick: () -> Unit = {}
+    onAppSettingsClick: () -> Unit = {}
 ) {
     val appColors = LocalAppColors.current
     val scrollState = rememberScrollState()