IndexedDB: Don't reset cursor prefetches on non-transactional calls

Cursor prefetch caches must be reset when requests that could invalidate
the cache are made (i.e. puts, deletes), and to ensure that requests
are processed in order per spec (i.e. even gets). This doesn't apply
to requests that aren't scoped to a transaction, so some unnecessary
resets can be removed.

BUG=329950
R=dgrogan

Review URL: https://codereview.chromium.org/128623003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243737 0039d316-1c4b-4281-b951-d872f2087c98

content/child/indexed_db/indexed_db_dispatcher.cc

@@ -219,7 +219,6 @@ void IndexedDBDispatcher::RequestIDBFactoryOpen(
     WebIDBCallbacks* callbacks_ptr,
     WebIDBDatabaseCallbacks* database_callbacks_ptr,
     const std::string& database_identifier) {
-  ResetCursorPrefetchCaches();
   scoped_ptr<WebIDBCallbacks> callbacks(callbacks_ptr);
   scoped_ptr<WebIDBDatabaseCallbacks> database_callbacks(
       database_callbacks_ptr);
@@ -239,7 +238,6 @@ void IndexedDBDispatcher::RequestIDBFactoryOpen(
 void IndexedDBDispatcher::RequestIDBFactoryGetDatabaseNames(
     WebIDBCallbacks* callbacks_ptr,
     const std::string& database_identifier) {
-  ResetCursorPrefetchCaches();
   scoped_ptr<WebIDBCallbacks> callbacks(callbacks_ptr);
 
   IndexedDBHostMsg_FactoryGetDatabaseNames_Params params;
@@ -253,7 +251,6 @@ void IndexedDBDispatcher::RequestIDBFactoryDeleteDatabase(
     const base::string16& name,
     WebIDBCallbacks* callbacks_ptr,
     const std::string& database_identifier) {
-  ResetCursorPrefetchCaches();
   scoped_ptr<WebIDBCallbacks> callbacks(callbacks_ptr);
 
   IndexedDBHostMsg_FactoryDeleteDatabase_Params params;
@@ -267,7 +264,6 @@ void IndexedDBDispatcher::RequestIDBFactoryDeleteDatabase(
 void IndexedDBDispatcher::RequestIDBDatabaseClose(
     int32 ipc_database_id,
     int32 ipc_database_callbacks_id) {
-  ResetCursorPrefetchCaches();
   Send(new IndexedDBHostMsg_DatabaseClose(ipc_database_id));
   // There won't be pending database callbacks if the transaction was aborted in
   // the initial upgradeneeded event handler.
@@ -718,6 +714,7 @@ void IndexedDBDispatcher::OnIntVersionChange(int32 ipc_thread_id,
 
 void IndexedDBDispatcher::ResetCursorPrefetchCaches(
     int32 ipc_exception_cursor_id) {
+  // TODO(jsbell): Only reset cursors from the same transaction.
   typedef std::map<int32, WebIDBCursorImpl*>::iterator Iterator;
   for (Iterator i = cursors_.begin(); i != cursors_.end(); ++i) {
     if (i->first == ipc_exception_cursor_id)