Add metrics for session storage

This CL adds two metrics related to session persistence:
- Net.DeviceBoundSessions.SessionStoreLoadDuration for how long it takes
  to load sessions.
- Net.DeviceBoundSessions.SessionStoreLoadSuccess for the success rate
  of loading sessions.

Bug: 388557900
Change-Id: I539df8f6e8271fe1f271667d60843fc06b0ad4e8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6288998
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: thefrog <thefrog@chromium.org>
Commit-Queue: Daniel Rubery <drubery@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1423445}

net/device_bound_sessions/session_store_impl.cc

@@ -6,6 +6,7 @@
 
 #include <algorithm>
 
+#include "base/metrics/histogram_functions.h"
 #include "base/sequence_checker.h"
 #include "base/task/sequenced_task_runner.h"
 #include "base/task/thread_pool.h"
@@ -125,10 +126,12 @@ void SessionStoreImpl::LoadSessions(LoadSessionsCallback callback) {
                      db_storage_path_, base::Unretained(table_manager_.get()),
                      base::Unretained(session_data_.get())),
       base::BindOnce(&SessionStoreImpl::OnDatabaseLoaded,
-                     weak_ptr_factory_.GetWeakPtr(), std::move(callback)));
+                     weak_ptr_factory_.GetWeakPtr(), std::move(callback),
+                     base::ElapsedTimer()));
 }
 
 void SessionStoreImpl::OnDatabaseLoaded(LoadSessionsCallback callback,
+                                        base::ElapsedTimer timer,
                                         DBStatus db_status) {
   db_status_ = db_status;
   SessionsMap sessions;
@@ -140,6 +143,10 @@ void SessionStoreImpl::OnDatabaseLoaded(LoadSessionsCallback callback,
       session_data_->DeleteData(keys_to_delete);
     }
   }
+  base::UmaHistogramBoolean("Net.DeviceBoundSessions.SessionStoreLoadSuccess",
+                            db_status == DBStatus::kSuccess);
+  base::UmaHistogramTimes("Net.DeviceBoundSessions.SessionStoreLoadDuration",
+                          timer.Elapsed());
   std::move(callback).Run(std::move(sessions));
 }
 

net/device_bound_sessions/session_store_impl.h

@@ -13,6 +13,7 @@
 #include "base/functional/callback_forward.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_refptr.h"
+#include "base/timer/elapsed_timer.h"
 #include "components/sqlite_proto/key_value_data.h"
 #include "components/sqlite_proto/key_value_table.h"
 #include "components/sqlite_proto/proto_table_manager.h"
@@ -79,7 +80,9 @@ class NET_EXPORT SessionStoreImpl : public SessionStore {
   FRIEND_TEST_ALL_PREFIXES(SessionStoreImplTest,
                            PruneLoadedEntryWithSessionMissingWrappedKey);
 
-  void OnDatabaseLoaded(LoadSessionsCallback callback, DBStatus status);
+  void OnDatabaseLoaded(LoadSessionsCallback callback,
+                        base::ElapsedTimer timer,
+                        DBStatus status);
 
   // Helper function called by `OnDatabaseLoaded` to prune out any invalid
   // entries found in the data loaded from disk. Returns a map of valid

tools/metrics/histograms/metadata/net/histograms.xml

@@ -1061,6 +1061,29 @@ chromium-metrics-reviews@google.com.
   </summary>
 </histogram>
 
+<histogram name="Net.DeviceBoundSessions.SessionStoreLoadDuration" units="ms"
+    expires_after="2026-02-18">
+  <owner>drubery@chromium.org</owner>
+  <owner>chrome-counter-abuse-alerts@google.com</owner>
+  <summary>
+    This records how long it took to load Device Bound Sessions
+    (https://github.com/w3c/webappsec-dbsc/blob/main/README.md) persisted to
+    disk. It is logged once at startup, when sessions are loaded.
+  </summary>
+</histogram>
+
+<histogram name="Net.DeviceBoundSessions.SessionStoreLoadSuccess"
+    enum="BooleanLoaded" expires_after="2026-02-18">
+  <owner>drubery@chromium.org</owner>
+  <owner>chrome-counter-abuse-alerts@google.com</owner>
+  <summary>
+    This records whether loading existing Device Bound Sessions
+    (https://github.com/w3c/webappsec-dbsc/blob/main/README.md) that were
+    persisted to disk succeeded. It is logged once at startup, when sessions are
+    loaded.
+  </summary>
+</histogram>
+
 <histogram name="Net.DeviceBoundSessions.TotalRequestDeferredDuration"
     units="ms" expires_after="2026-02-18">
   <owner>drubery@chromium.org</owner>