IDBObserver: Lifetime Management: Adding Observer

content/browser/indexed_db/indexed_db_dispatcher_host.cc

Index: content/browser/indexed_db/indexed_db_dispatcher_host.cc
diff --git a/content/browser/indexed_db/indexed_db_dispatcher_host.cc b/content/browser/indexed_db/indexed_db_dispatcher_host.cc
index 6268ef02d5f4737490422dbb5b33d76695503290..553cfada19304f72b907884c49dd91a3ee8cc17e 100644
--- a/content/browser/indexed_db/indexed_db_dispatcher_host.cc
+++ b/content/browser/indexed_db/indexed_db_dispatcher_host.cc
@@ -193,26 +193,16 @@ int32_t IndexedDBDispatcherHost::Add(IndexedDBConnection* connection,
   return ipc_database_id;
 }
 
-int64_t IndexedDBDispatcherHost::HostObserverId(int64_t observer_id) {
-  // Inject the renderer process id into the observer id, to
-  // uniquely identify this observer, and effectively bind it to
-  // the renderer that initiated it. The lower 32 bits of
-  // observer_id are guaranteed to be unique within that renderer.
-  base::ProcessId pid = peer_pid();
-  DCHECK(!(observer_id >> 32)) << "observer ids can only be 32 bits";
-  static_assert(sizeof(base::ProcessId) <= sizeof(int32_t),
-                "Process ID must fit in 32 bits");
-
-  return observer_id | (static_cast<uint64_t>(pid) << 32);
+int64_t IndexedDBDispatcherHost::DatabaseDispatcherHost::GenerateObserverId(
+    int32_t observer_id,
+    int32_t ipc_thread_id) {
+  // Basic djb2 hash.
+  int64_t hash = 5381;
+  hash = ((hash << 5) + hash) + ipc_thread_id;
+  hash = ((hash << 5) + hash) + observer_id;
+  return hash;
 }
 
-int64_t IndexedDBDispatcherHost::RendererObserverId(int64_t host_observer_id) {
-  DCHECK(host_observer_id >> 32 == peer_pid())
-      << "Invalid renderer target for observer id";
-  return host_observer_id & 0xffffffff;
-}
-
-// Do I need this for observer? origin?
 void IndexedDBDispatcherHost::RegisterTransactionId(int64_t host_transaction_id,
                                                     const url::Origin& origin) {
   if (!database_dispatcher_host_)
@@ -654,17 +644,39 @@ void IndexedDBDispatcherHost::DatabaseDispatcherHost::OnObserve(
     int32_t ipc_thread_id,
     int32_t ipc_database_id,
     int64_t transaction_id,
-    int64_t observer_id) {
+    int32_t observer_id) {
+  DCHECK(parent_->context()->TaskRunner()->RunsTasksOnCurrentThread());
+  IndexedDBConnection* connection =
+      parent_->GetOrTerminateProcess(&map_, ipc_database_id);
+  if (!connection || !connection->IsConnected())
+    return;
+  int64_t host_observer_id = GenerateObserverId(observer_id, ipc_thread_id);
+  observers_.push_back(host_observer_id);
+  connection->database()->Observe(parent_->HostTransactionId(transaction_id),
+                                  host_observer_id);
+}
+
+void IndexedDBDispatcherHost::DatabaseDispatcherHost::OnUnobserve(
+    int32_t ipc_thread_id,
+    int32_t ipc_database_id,
+    std::vector<int32_t> remove_observers) {
   DCHECK(parent_->context()->TaskRunner()->RunsTasksOnCurrentThread());
   IndexedDBConnection* connection =
       parent_->GetOrTerminateProcess(&map_, ipc_database_id);
   if (!connection || !connection->IsConnected())
     return;
+  std::vector<int64_t> observersToRemove =
+      RemoveObservers(remove_observers, ipc_thread_id);
+  connection->database()->Unobserve(observersToRemove);
+}
 
-  observers_.push_back(observer_id);
-  connection->database()->Observe(                     // pass thread_id here
-      parent_->HostTransactionId(transaction_id),
-      parent_->HostObserverId(observer_id));
+std::vector<int64_t>
+IndexedDBDispatcherHost::DatabaseDispatcherHost::RemoveObservers(
+    std::vector<int32_t> remove_observers,
+    int32_t ipc_database_id) {
+  // TODO(palakj): remove from observers_ and return vector of the hashed id.
+  std::vector<int64_t> observersToRemove;
+  return observersToRemove;
 }
 
 void IndexedDBDispatcherHost::DatabaseDispatcherHost::OnGet(