Notify observers when Attribution Reporting data is deleted by key

Otherwise, the Attribution Internals UI will not be updated promptly,
causing misleading data to be shown indefinitely.

(cherry picked from commit b9556b0)

Bug: 1449219
Change-Id: I61159ba12d8f6f4bec7b88e1de90452bda2420dd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4568989
Commit-Queue: Andrew Paseltiner <apaseltiner@chromium.org>
Reviewed-by: Nan Lin <linnan@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1149708}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4568876
Auto-Submit: Andrew Paseltiner <apaseltiner@chromium.org>
Commit-Queue: Nan Lin <linnan@chromium.org>
Cr-Commit-Position: refs/branch-heads/5790@{#129}
Cr-Branched-From: 1d71a33-refs/heads/main@{#1148114}

content/browser/attribution_reporting/attribution_manager_impl.cc

@@ -958,7 +958,18 @@ void AttributionManagerImpl::RemoveAttributionDataByDataKey(
     base::OnceClosure callback) {
   attribution_storage_.AsyncCall(&AttributionStorage::DeleteByDataKey)
       .WithArgs(data_key)
-      .Then(std::move(callback));
+      .Then(std::move(callback).Then(
+          // TODO(crbug.com/1446693): Replace this lambda with
+          // `OnClearDataComplete()` so that observers are notified and the
+          // task-runner priority is restored.
+          base::BindOnce(
+              [](base::WeakPtr<AttributionManagerImpl> manager) {
+                if (manager) {
+                  manager->NotifySourcesChanged();
+                  manager->NotifyReportsChanged();
+                }
+              },
+              weak_factory_.GetWeakPtr())));
 }
 
 void AttributionManagerImpl::GetReportsToSend() {

content/browser/attribution_reporting/attribution_manager_impl_unittest.cc

@@ -61,6 +61,7 @@
 #include "content/browser/attribution_reporting/test/mock_content_browser_client.h"
 #include "content/browser/browsing_data/browsing_data_filter_builder_impl.h"
 #include "content/browser/storage_partition_impl.h"
+#include "content/public/browser/attribution_data_model.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browsing_data_filter_builder.h"
 #include "content/public/browser/global_routing_id.h"
@@ -2839,6 +2840,24 @@ TEST_F(AttributionManagerImplTest, PendingReportsMetrics_OverLimits) {
       (base::Seconds(10) * kMaxPendingReportsTimings).InMilliseconds());
 }
 
+TEST_F(AttributionManagerImplTest,
+       RemoveAttributionDataByDataKey_NotifiesObservers) {
+  MockAttributionObserver observer;
+  base::ScopedObservation<AttributionManager, AttributionObserver> observation(
+      &observer);
+  observation.Observe(attribution_manager_.get());
+
+  EXPECT_CALL(observer, OnSourcesChanged);
+  EXPECT_CALL(observer, OnReportsChanged);
+
+  base::RunLoop run_loop;
+  attribution_manager_->RemoveAttributionDataByDataKey(
+      AttributionDataModel::DataKey(
+          url::Origin::Create(GURL("https://x.test"))),
+      run_loop.QuitClosure());
+  run_loop.Run();
+}
+
 class AttributionManagerImplDebugReportTest
     : public AttributionManagerImplTest {
  protected: