[fenix] Post: move group removal logic into PagedHistoryProvider

This moves the group removal logic to the place where the groups are
actually formed. This helps clean-up the fragment code a bit, and
removes the awkward 'allow mutate some random internal state' API from
the provider.

app/src/main/java/org/mozilla/fenix/components/history/PagedHistoryProvider.kt

@@ -104,13 +104,31 @@ class DefaultPagedHistoryProvider(
         }
     }
 
+    /**
+     * Removes [group] and any corresponding history visits.
+     */
+    suspend fun deleteHistoryGroup(group: History.Group) {
+        for (historyMetadata in group.items) {
+            getMatchingHistory(historyMetadata)?.let {
+                historyStorage.deleteVisit(
+                    url = it.url,
+                    timestamp = it.visitTime
+                )
+            }
+        }
+
+        historyStorage.deleteHistoryMetadata(
+            searchTerm = group.title
+        )
+
+        // Force a re-fetch of the groups next time we go through #getHistory.
+        historyGroups = null
+    }
+
     /**
      * Returns the [History.Regular] corresponding to the given [History.Metadata] item.
-     *
-     * @param historyMetadata The [History.Metadata] to match.
-     * @return the [History.Regular] corresponding to the given [History.Metadata] item or null.
      */
-    suspend fun getMatchingHistory(historyMetadata: History.Metadata): VisitInfo? {
+    private suspend fun getMatchingHistory(historyMetadata: History.Metadata): VisitInfo? {
         val history = historyStorage.getDetailedVisits(
             start = historyMetadata.visitedAt - BUFFER_TIME,
             end = historyMetadata.visitedAt + BUFFER_TIME,
@@ -121,13 +139,6 @@ class DefaultPagedHistoryProvider(
             .minByOrNull { abs(historyMetadata.visitedAt - it.visitTime) }
     }
 
-    /**
-     * Clears the history groups to refetch the most history metadata after any changes.
-     */
-    fun clearHistoryGroups() {
-        historyGroups = null
-    }
-
     @Suppress("MagicNumber")
     private suspend fun getHistoryAndSearchGroups(
         offset: Long,

app/src/main/java/org/mozilla/fenix/library/history/HistoryFragment.kt

@@ -355,26 +355,11 @@ class HistoryFragment : LibraryPageFragment<History>(), UserInteractionHandler {
                     for (item in items) {
                         analytics.metrics.track(Event.HistoryItemRemoved)
 
-                        if (item is History.Regular) {
-                            core.historyStorage.deleteVisit(
-                                url = item.url,
-                                timestamp = item.visitedAt
-                            )
-                        } else if (item is History.Group) {
-                            for (historyMetadata in item.items) {
-                                historyProvider.getMatchingHistory(historyMetadata)?.let {
-                                    core.historyStorage.deleteVisit(
-                                        url = it.url,
-                                        timestamp = it.visitTime
-                                    )
-                                }
-                            }
-
-                            core.historyStorage.deleteHistoryMetadata(
-                                searchTerm = item.title
-                            )
-
-                            historyProvider.clearHistoryGroups()
+                        when (item) {
+                            is History.Regular -> core.historyStorage.deleteVisit(item.url, item.visitedAt)
+                            is History.Group -> historyProvider.deleteHistoryGroup(item)
+                            // We won't encounter individual metadata entries outside of groups.
+                            is History.Metadata -> {}
                         }
                     }
                 }