[fenix] For https://github.com/mozilla-mobile/fenix/issues/11406 - Scrolls to selected tab when switching modes

app/src/main/java/org/mozilla/fenix/tabtray/TabTrayView.kt

@@ -122,7 +122,7 @@ class TabTrayView(
                     }
                     if (!hasLoaded) {
                         hasLoaded = true
-                        tray.layoutManager?.scrollToPosition(selectedBrowserTabIndex)
+                        scrollToSelectedTab()
                         if (view.context.settings().accessibilityServicesEnabled) {
                             lifecycleScope.launch {
                                 delay(SELECTION_DELAY.toLong())
@@ -194,6 +194,7 @@ class TabTrayView(
         filterTabs.invoke(filter)
 
         updateState(view.context.components.core.store.state)
+        scrollToSelectedTab()
     }
 
     override fun onTabReselected(tab: TabLayout.Tab?) { /*noop*/ }
@@ -225,6 +226,20 @@ class TabTrayView(
         }
     }
 
+    fun setTopOffset(landscape: Boolean) {
+        val topOffset = if (landscape) {
+            0
+        } else {
+            view.context.resources.getDimension(R.dimen.tab_tray_top_offset).toInt()
+        }
+
+        behavior.setExpandedOffset(topOffset)
+    }
+
+    fun dismissMenu() {
+        menu?.dismiss()
+    }
+
     private fun toggleFabText(private: Boolean) {
         if (private) {
             fabView.new_tab_button.extend()
@@ -235,18 +250,19 @@ class TabTrayView(
         }
     }
 
-    fun setTopOffset(landscape: Boolean) {
-        val topOffset = if (landscape) {
-            0
+    private fun scrollToSelectedTab() {
+        (view.tabsTray as? BrowserTabsTray)?.also { tray ->
+            val tabs = if (isPrivateModeSelected) {
+                view.context.components.core.store.state.privateTabs
             } else {
-            view.context.resources.getDimension(R.dimen.tab_tray_top_offset).toInt()
+                view.context.components.core.store.state.normalTabs
             }
 
-        behavior.setExpandedOffset(topOffset)
-    }
+            val selectedBrowserTabIndex = tabs
+                .indexOfFirst { it.id == view.context.components.core.store.state.selectedTabId }
 
-    fun dismissMenu() {
-        menu?.dismiss()
+            tray.layoutManager?.scrollToPosition(selectedBrowserTabIndex)
+        }
     }
 
     companion object {