Purge new localstorage memory cache when under memory pressure.

content/browser/dom_storage/local_storage_context_mojo.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_DOM_STORAGE_LOCAL_STORAGE_CONTEXT_MOJO_H_
 #define CONTENT_BROWSER_DOM_STORAGE_LOCAL_STORAGE_CONTEXT_MOJO_H_
 
 #include <memory>
 
 #include "base/files/file_path.h"
@@ skipping 27 matching lines @@
   ~LocalStorageContextMojo();
 
   void OpenLocalStorage(const url::Origin& origin,
                         mojom::LevelDBWrapperRequest request);
   void GetStorageUsage(GetStorageUsageCallback callback);
   void DeleteStorage(const url::Origin& origin);
   // Like DeleteStorage(), but also deletes storage for all sub-origins.
   void DeleteStorageForPhysicalOrigin(const url::Origin& origin);
   void Flush();
 
+  // Clears any caches, to free up as much memory as possible. Next access to
+  // storage for a particular origin will reload the data from the database.
+  void PurgeMemory();
+
   leveldb::mojom::LevelDBDatabaseAssociatedRequest DatabaseRequestForTesting();
 
  private:
   friend class MojoDOMStorageBrowserTest;
 
   class LevelDBWrapperHolder;
 
   // Runs |callback| immediately if already connected to a database, otherwise
   // delays running |callback| untill after a connection has been established.
   // Initiates connecting to the database if no connection is in progres yet.
@@ skipping 58 matching lines @@
   // Used to access old data for migration.
   scoped_refptr<DOMStorageTaskRunner> task_runner_;
   base::FilePath old_localstorage_path_;
 
   base::WeakPtrFactory<LocalStorageContextMojo> weak_ptr_factory_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOM_STORAGE_LOCAL_STORAGE_CONTEXT_MOJO_H_