[memories] Merge ClusterVisitDatabase into VisitAnnotationsDatabase.

This is CL 5 of 5 merging `ClusterVisitDatabase` with
`VisitAnnotationsDatabase`.

`ClusterVisitDatabase` previously stored `context_annotations`, while
`VisitAnnotationsDatabase` stored `content_annotations`.

With this CL, `VisitAnnotationsDatabase` stores both tables.

Bug: 1179068, 1184879, 1184875, 1171352
Change-Id: I5aea4714a96e485155b1364addaaea8ac808baf9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2876080
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#881048}

components/history/core/browser/BUILD.gn

@@ -7,8 +7,6 @@ static_library("browser") {
     "browsing_history_driver.h",
     "browsing_history_service.cc",
     "browsing_history_service.h",
-    "cluster_visit_database.cc",
-    "cluster_visit_database.h",
     "domain_mixing_metrics.cc",
     "domain_mixing_metrics.h",
     "download_constants.h",
@@ -199,7 +197,6 @@ source_set("unit_tests") {
   testonly = true
   sources = [
     "browsing_history_service_unittest.cc",
-    "cluster_visit_database_unittest.cc",
     "domain_mixing_metrics_unittest.cc",
     "download_slice_info_unittest.cc",
     "expire_history_backend_unittest.cc",

components/history/core/browser/expire_history_backend.cc

@@ -473,8 +473,8 @@ void ExpireHistoryBackend::DeleteVisitRelatedInfo(const VisitVector& visits,
         effects->affected_urls[visit.url_id] = row;
     }
 
-    // Delete content annotations associated with visit.
-    main_db_->DeleteContentAnnotationsForVisit(visit.visit_id);
+    // Delete content & context annotations associated with visit.
+    main_db_->DeleteAnnotationsForVisit(visit.visit_id);
   }
 }