Reland: [IndexedDB] Delete callbacks state on worker thread exit.

content/child/indexed_db/indexed_db_dispatcher.cc

Index: content/child/indexed_db/indexed_db_dispatcher.cc
diff --git a/content/child/indexed_db/indexed_db_dispatcher.cc b/content/child/indexed_db/indexed_db_dispatcher.cc
index 4189fdfed76e851e98dd279bc78241449d02b03e..26084c777bf20d039131865920dcfecead845f34 100644
--- a/content/child/indexed_db/indexed_db_dispatcher.cc
+++ b/content/child/indexed_db/indexed_db_dispatcher.cc
@@ -36,6 +36,10 @@ IndexedDBDispatcher::IndexedDBDispatcher() {
 }
 
 IndexedDBDispatcher::~IndexedDBDispatcher() {
+  in_destructor_ = true;
+  mojo_owned_callback_state_.clear();
+  mojo_owned_database_callback_state_.clear();
+
   g_idb_dispatcher_tls.Pointer()->Set(kHasBeenDeleted);
 }
 
@@ -98,24 +102,34 @@ void IndexedDBDispatcher::RemoveObservers(
 
 void IndexedDBDispatcher::RegisterMojoOwnedCallbacks(
     IndexedDBCallbacksImpl::InternalState* callbacks) {
-  mojo_owned_callback_state_.insert(callbacks);
+  mojo_owned_callback_state_[callbacks] = base::WrapUnique(callbacks);
 }
 
 void IndexedDBDispatcher::UnregisterMojoOwnedCallbacks(
     IndexedDBCallbacksImpl::InternalState* callbacks) {
-  DCHECK(base::ContainsValue(mojo_owned_callback_state_, callbacks));
-  mojo_owned_callback_state_.erase(callbacks);
+  if (in_destructor_)
+    return;
+
+  auto it = mojo_owned_callback_state_.find(callbacks);
+  DCHECK(it != mojo_owned_callback_state_.end());
+  it->second.release();
+  mojo_owned_callback_state_.erase(it);
 }
 
 void IndexedDBDispatcher::RegisterMojoOwnedDatabaseCallbacks(
     blink::WebIDBDatabaseCallbacks* callbacks) {
-  mojo_owned_database_callback_state_.insert(callbacks);
+  mojo_owned_database_callback_state_[callbacks] = base::WrapUnique(callbacks);
 }
 
 void IndexedDBDispatcher::UnregisterMojoOwnedDatabaseCallbacks(
     blink::WebIDBDatabaseCallbacks* callbacks) {
-  DCHECK(base::ContainsValue(mojo_owned_database_callback_state_, callbacks));
-  mojo_owned_database_callback_state_.erase(callbacks);
+  if (in_destructor_)
+    return;
+
+  auto it = mojo_owned_database_callback_state_.find(callbacks);
+  DCHECK(it != mojo_owned_database_callback_state_.end());
+  it->second.release();
+  mojo_owned_database_callback_state_.erase(it);
 }
 
 void IndexedDBDispatcher::OnDatabaseChanges(