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..5b1b5bd63c3d0d21a1fab3aa4df0471647d98d96 100644
--- a/content/browser/dom_storage/dom_storage_database.cc
+++ b/content/browser/dom_storage/dom_storage_database.cc
@@ -68,6 +68,9 @@ void DOMStorageDatabase::ReadAllValues(DOMStorageValuesMap* result) {
     (*result)[key] = base::NullableString16(value, false);
   }
   known_to_be_empty_ = result->empty();
+
+  // Reduce the size of sqlite caches.
+  db_->TrimMemory(false /* aggressively */);
 }
 
 bool DOMStorageDatabase::CommitChanges(bool clear_all_first,
@@ -125,6 +128,10 @@ bool DOMStorageDatabase::CommitChanges(bool clear_all_first,
   bool success = transaction.Commit();
   if (!success)
     known_to_be_empty_ = old_known_to_be_empty;
+
+  // Reduce the size of sqlite caches.
+  db_->TrimMemory(false /* aggressively */);
+
   return success;
 }