UKM that threads together multiple form interaction events.

components/ukm/test_ukm_service.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/test_ukm_service.h"
 
+#include "base/logging.h"
+#include "base/metrics/metrics_hashes.h"
+#include "components/ukm/ukm_entry.h"
 #include "components/ukm/ukm_source.h"
 
 namespace ukm {
 
 UkmServiceTestingHarness::UkmServiceTestingHarness() {
   UkmService::RegisterPrefs(test_prefs_.registry());
   test_prefs_.ClearPref(prefs::kUkmClientId);
   test_prefs_.ClearPref(prefs::kUkmSessionId);
   test_prefs_.ClearPref(prefs::kUkmPersistedLogs);
 
   test_ukm_service_ = base::MakeUnique<TestUkmService>(&test_prefs_);
 }
 
 UkmServiceTestingHarness::~UkmServiceTestingHarness() = default;
 
 TestUkmService::TestUkmService(PrefService* prefs_service)
     : UkmService(prefs_service, &test_metrics_service_client_) {
   EnableRecording();
   DisableReporting();
 }
 
 TestUkmService::~TestUkmService() = default;
 
 const std::map<int32_t, std::unique_ptr<UkmSource>>&
 TestUkmService::GetSources() const {
   return sources_for_testing();
 }
 
 const UkmSource* TestUkmService::GetSourceForUrl(const char* url) const {
+  const UkmSource* source = nullptr;
   for (const auto& kv : sources_for_testing()) {
-    if (kv.second->url() == url)
-      return kv.second.get();
+    if (kv.second->url() == url) {
+      DCHECK_EQ(nullptr, source);
+      source = kv.second.get();
+    }
   }
-  return nullptr;
+  return source;
+}
+
+const UkmSource* TestUkmService::GetSourceForSourceId(int32_t source_id) const {
+  const UkmSource* source = nullptr;
+  for (const auto& kv : sources_for_testing()) {
+    if (kv.second->id() == source_id) {
+      DCHECK_EQ(nullptr, source);
+      source = kv.second.get();
+    }
+  }
+  return source;
 }
 
 const UkmEntry* TestUkmService::GetEntry(size_t entry_num) const {
   return entries_for_testing()[entry_num].get();
 }
 
+const UkmEntry* TestUkmService::GetEntryForEntryName(
+    const char* entry_name) const {
+  for (const auto& it : entries_for_testing()) {
+    if (it->event_hash() == base::HashMetricName(entry_name))
+      return it.get();
+  }
+  return nullptr;
+}
+
 }  // namespace ukm