Basic UkmService implementation

components/ukm/observers/history_delete_observer.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/ukm/observers/history_delete_observer.h"
+
+#include "components/history/core/browser/history_service.h"
+
+namespace ukm {
+
+HistoryDeleteObserver::HistoryDeleteObserver() = default;
+
+HistoryDeleteObserver::~HistoryDeleteObserver() {
+  for (history::HistoryService* history_service : observed_history_services_) {
+    history_service->RemoveObserver(this);
+  }
+}
+
+void HistoryDeleteObserver::ObserveServiceForDeletions(
+    history::HistoryService* history_service) {
+  if (history_service) {
+    history_service->AddObserver(this);
+    observed_history_services_.insert(history_service);
+  }
+}
+
+void HistoryDeleteObserver::OnURLsDeleted(
+    history::HistoryService* history_service,
+    bool all_history,
+    bool expired,
+    const history::URLRows& deleted_rows,
+    const std::set<GURL>& favicon_urls) {
+  if (!expired)
+    OnHistoryDeleted();
+}
+
+void HistoryDeleteObserver::HistoryServiceBeingDeleted(
+    history::HistoryService* history_service) {
+  history_service->RemoveObserver(this);
+  observed_history_services_.erase(history_service);
+}
+
+}  // namespace ukm