[UKM] Create a Source ID type for metrics with no URL

Also whitelist it, so it is not omitted when logging metrics.
Adds convenience ukm::NoIdentifierSourceId() to get a source id of this
new type.

cc/trees/layer_tree_host_unittest_checkerimaging.cc was updated as it was
triggering the new DCHECK in components/ukm/ukm_recorder_impl.cc

Bug: 1204578
Change-Id: I13a85fa22aea58899618dd69a514ac9a8949d130
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2863253
Reviewed-by: Yue Ru Sun <yrsun@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Javier Flores <javierrobles@chromium.org>
Cr-Commit-Position: refs/heads/master@{#879423}

cc/trees/layer_tree_host_unittest_checkerimaging.cc

@@ -20,8 +20,9 @@ const char kCheckerboardImagesMetric[] = "CheckerboardedImagesCount";
 
 class LayerTreeHostCheckerImagingTest : public LayerTreeTest {
  public:
-  LayerTreeHostCheckerImagingTest() : url_(GURL("https://example.com")),
-                                      ukm_source_id_(123) {}
+  LayerTreeHostCheckerImagingTest()
+      : url_(GURL("https://example.com")),
+        ukm_source_id_(ukm::AssignNewSourceId()) {}
 
   void BeginTest() override {
     layer_tree_host()->SetSourceURL(ukm_source_id_, url_);
@@ -36,8 +37,9 @@ class LayerTreeHostCheckerImagingTest : public LayerTreeTest {
     recorder->UpdateSourceURL(ukm_source_id_, url_);
 
     // Change the source to ensure any accumulated metrics are flushed.
-    impl->ukm_manager()->SetSourceId(200);
-    recorder->UpdateSourceURL(200, GURL("chrome://test2"));
+    ukm::SourceId newSourceId = ukm::AssignNewSourceId();
+    impl->ukm_manager()->SetSourceId(newSourceId);
+    recorder->UpdateSourceURL(newSourceId, GURL("chrome://test2"));
 
     const auto& entries = recorder->GetEntriesByName(kRenderingEvent);
     ASSERT_EQ(1u, entries.size());

components/ukm/ukm_recorder_impl.cc

@@ -48,11 +48,11 @@ std::string GetWhitelistEntries() {
 }
 
 bool IsWhitelistedSourceId(SourceId source_id) {
-  return GetSourceIdType(source_id) == SourceIdType::NAVIGATION_ID ||
-         GetSourceIdType(source_id) == SourceIdType::APP_ID ||
-         GetSourceIdType(source_id) == SourceIdType::HISTORY_ID ||
-         GetSourceIdType(source_id) == SourceIdType::WEBAPK_ID ||
-         GetSourceIdType(source_id) == SourceIdType::PAYMENT_APP_ID;
+  SourceIdType type = GetSourceIdType(source_id);
+  return type == SourceIdType::NAVIGATION_ID || type == SourceIdType::APP_ID ||
+         type == SourceIdType::HISTORY_ID || type == SourceIdType::WEBAPK_ID ||
+         type == SourceIdType::PAYMENT_APP_ID ||
+         type == SourceIdType::NO_URL_ID;
 }
 
 // Returns whether |url| has one of the schemes supported for logging to UKM.
@@ -337,10 +337,12 @@ void UkmRecorderImpl::StoreRecordingsInReport(Report* report) {
   for (const auto& kv : recordings_.sources) {
     // Don't keep sources of these types after current report because their
     // entries are logged only at source creation time.
-    if (GetSourceIdType(kv.first) == ukm::SourceIdObj::Type::APP_ID ||
-        GetSourceIdType(kv.first) == ukm::SourceIdObj::Type::HISTORY_ID ||
-        GetSourceIdType(kv.first) == ukm::SourceIdObj::Type::WEBAPK_ID ||
-        GetSourceIdType(kv.first) == SourceIdType::PAYMENT_APP_ID) {
+    SourceIdType type = GetSourceIdType(kv.first);
+    if (type == ukm::SourceIdObj::Type::APP_ID ||
+        type == ukm::SourceIdObj::Type::HISTORY_ID ||
+        type == ukm::SourceIdObj::Type::WEBAPK_ID ||
+        type == SourceIdType::PAYMENT_APP_ID ||
+        type == SourceIdType::NO_URL_ID) {
       MarkSourceForDeletion(kv.first);
     }
     // If the source id is not whitelisted, don't send it unless it has
@@ -579,6 +581,7 @@ int UkmRecorderImpl::PruneOldSources(size_t max_kept_sources) {
 void UkmRecorderImpl::UpdateSourceURL(SourceId source_id,
                                       const GURL& unsanitized_url) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  DCHECK(GetSourceIdType(source_id) != SourceIdType::NO_URL_ID);
 
   if (base::Contains(recordings_.sources, source_id))
     return;

services/metrics/public/cpp/ukm_source_id.cc

@@ -82,4 +82,11 @@ SourceIdType GetSourceIdType(SourceId source_id) {
   return ukm::SourceIdObj::FromInt64(source_id).GetType();
 }
 
+SourceId NoURLSourceId() {
+  static const SourceId source_id =
+      SourceIdObj::FromOtherId(AssignNewSourceId(), SourceIdType::NO_URL_ID)
+          .ToInt64();
+  return source_id;
+}
+
 }  // namespace ukm

services/metrics/public/cpp/ukm_source_id.h

@@ -66,7 +66,12 @@ class METRICS_EXPORT SourceIdObj {
     // shared workers and service workers). Shared workers and service workers
     // can be connected to multiple clients (e.g. documents or other workers).
     WORKER_ID = 7,
-    kMaxValue = WORKER_ID,
+    // Source ID type for metrics that doesn't need to be associated with a
+    // specific URL. Metrics with this type will be whitelisted and always
+    // recorded. A source ID of this type can be obtained with NoURLSourceId().
+    NO_URL_ID = 8,
+
+    kMaxValue = NO_URL_ID,
   };
 
   // Default constructor has the invalid value.
@@ -119,6 +124,9 @@ METRICS_EXPORT SourceId AssignNewSourceId();
 METRICS_EXPORT SourceId ConvertToSourceId(int64_t other_id,
                                           SourceIdType id_type);
 
+// Utility for getting source ID with NO_URL_ID type.
+METRICS_EXPORT SourceId NoURLSourceId();
+
 // Get the SourceIdType of the SourceId object.
 METRICS_EXPORT SourceIdType GetSourceIdType(SourceId source_id);