Purge browser cache for dom storage in a smarter way

content/browser/dom_storage/dom_storage_database.cc

Index: content/browser/dom_storage/dom_storage_database.cc
diff --git a/content/browser/dom_storage/dom_storage_database.cc b/content/browser/dom_storage/dom_storage_database.cc
index b19dffa6c2fb947c499cc8cb854b3d388f8a0a06..9983f624737866f20225e85c34c386be7cc3c328 100644
--- a/content/browser/dom_storage/dom_storage_database.cc
+++ b/content/browser/dom_storage/dom_storage_database.cc
@@ -128,6 +128,11 @@ bool DOMStorageDatabase::CommitChanges(bool clear_all_first,
   return success;
 }
 
+void DOMStorageDatabase::TrimDatabase() {
+  // We hit this case only on aggressive purging.
+  db_->TrimMemory(true /* aggressively */);

[michaeln, 2016/05/09 21:50:31]

This needs to have a test for IsOpen() or an assertion that it's only called
when IsOpen().

If we do decide to do this unconditionally on each read/write, the ReadAll and
Commit methods could call db_->TrimMem() directly w/o exposing this as a public
method.

[ssid, 2016/05/10 02:04:16]

Fixed.
Sorry I do not understand how do i get the pointer to sql::Connection from
DOMStorageArea. It only holds an object of DOMStorageDatabaseAdapter.
I would have to write:
reinterpret_cast<DOMStorageDatabase*>(backing_.get())->db_->TrimMemory(false);

And also add DOMStorageArea as friend of DOMStorageDatabase.

Am I missing something here?

+}
+
 bool DOMStorageDatabase::LazyOpen(bool create_if_needed) {
   if (failed_to_open_) {
     // Don't try to open a database that we know has failed