For #9425 - SearchFragment now reacts to undo operation for custom engines

When you remove a search engine from our list, an undo snackbar that outlives the fragment is shown. If you go back to the search fragment and press undo, now the shortcut list gets updated

app/src/main/java/org/mozilla/fenix/components/searchengine/CustomSearchEngineStore.kt

@@ -6,7 +6,6 @@ package org.mozilla.fenix.components.searchengine
 
 import android.content.Context
 import android.content.SharedPreferences
-import androidx.annotation.VisibleForTesting
 import mozilla.components.browser.icons.IconRequest
 import mozilla.components.browser.search.SearchEngine
 import mozilla.components.browser.search.SearchEngineParser
@@ -125,7 +124,6 @@ object CustomSearchEngineStore {
         }
     }
 
-    private const val PREF_KEY_CUSTOM_SEARCH_ENGINES = "pref_custom_search_engines"
-    @VisibleForTesting
+    const val PREF_KEY_CUSTOM_SEARCH_ENGINES = "pref_custom_search_engines"
     const val PREF_FILE_SEARCH_ENGINES = "custom-search-engines"
 }

app/src/main/java/org/mozilla/fenix/search/SearchFragment.kt

@@ -46,6 +46,7 @@ import org.mozilla.fenix.HomeActivity
 import org.mozilla.fenix.R
 import org.mozilla.fenix.components.StoreProvider
 import org.mozilla.fenix.components.metrics.Event
+import org.mozilla.fenix.components.searchengine.CustomSearchEngineStore
 import org.mozilla.fenix.ext.components
 import org.mozilla.fenix.ext.getSpannable
 import org.mozilla.fenix.ext.hideToolbar
@@ -54,6 +55,7 @@ import org.mozilla.fenix.ext.settings
 import org.mozilla.fenix.search.awesomebar.AwesomeBarView
 import org.mozilla.fenix.search.toolbar.ToolbarView
 import org.mozilla.fenix.settings.SupportUtils
+import org.mozilla.fenix.settings.registerOnSharedPreferenceChangeListener
 import org.mozilla.fenix.widget.VoiceSearchActivity.Companion.SPEECH_REQUEST_CODE
 
 @Suppress("TooManyFunctions", "LargeClass")
@@ -128,6 +130,8 @@ class SearchFragment : Fragment(), UserInteractionHandler {
 
         awesomeBarView = AwesomeBarView(view.scrollable_area, searchInteractor,
             view.findViewById(R.id.awesomeBar))
+        setShortcutsChangedListener()
+
         view.scrollView.setOnScrollChangeListener {
                 _: NestedScrollView, _: Int, _: Int, _: Int, _: Int ->
             view.hideKeyboard()
@@ -164,6 +168,17 @@ class SearchFragment : Fragment(), UserInteractionHandler {
         return (speechIntent.resolveActivity(requireContext().packageManager) != null)
     }
 
+    private fun setShortcutsChangedListener() {
+        requireContext().getSharedPreferences(
+            CustomSearchEngineStore.PREF_FILE_SEARCH_ENGINES,
+            Context.MODE_PRIVATE
+        ).registerOnSharedPreferenceChangeListener(viewLifecycleOwner) { _, key ->
+            if (key == CustomSearchEngineStore.PREF_KEY_CUSTOM_SEARCH_ENGINES) {
+                awesomeBarView.update(searchStore.state)
+            }
+        }
+    }
+
     private fun launchVoiceSearch() {
         // Note if a user disables speech while the app is on the search fragment
         // the voice button will still be available and *will* cause a crash if tapped,