ExtensionStorageMonitor: use smaller, self-registering StorageObservers

chrome/browser/extensions/extension_storage_monitor.h

 // Copyright 2014 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 CHROME_BROWSER_EXTENSIONS_EXTENSION_STORAGE_MONITOR_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_STORAGE_MONITOR_H_
 
 #include <stdint.h>
 
 #include <set>
@@ skipping 14 matching lines @@
 
 namespace gfx {
 class Image;
 }
 
 namespace extensions {
 
 class Extension;
 class ExtensionPrefs;
 class ExtensionRegistry;
-class StorageEventObserver;
+class ExtensionStorageMonitorIOHelper;
 
 // ExtensionStorageMonitor monitors the storage usage of extensions and apps
 // that are granted unlimited storage and displays notifications when high
 // usage is detected.
 class ExtensionStorageMonitor : public KeyedService,
                                 public content::NotificationObserver,
                                 public ExtensionRegistryObserver,
                                 public ExtensionUninstallDialog::Delegate {
  public:
   static ExtensionStorageMonitor* Get(content::BrowserContext* context);
@@ skipping 86 matching lines @@
   std::set<std::string> notified_extension_ids_;
 
   content::BrowserContext* context_;
   extensions::ExtensionPrefs* extension_prefs_;
 
   content::NotificationRegistrar registrar_;
   ScopedObserver<extensions::ExtensionRegistry,
                  extensions::ExtensionRegistryObserver>
       extension_registry_observer_;
 
-  // StorageEventObserver monitors storage for extensions on the IO thread.
-  scoped_refptr<StorageEventObserver> storage_observer_;
+  // ExtensionStorageMonitorIOHelper maintains, on the IO thread, an instance of
+  // SingleExtensionStorageObserver for each extension.
+  scoped_refptr<ExtensionStorageMonitorIOHelper> io_helper_;
 
   // Modal dialog used to confirm removal of an extension.
   std::unique_ptr<ExtensionUninstallDialog> uninstall_dialog_;
 
   // The ID of the extension that is the subject of the uninstall confirmation
   // dialog.
   std::string uninstall_extension_id_;
 
   base::WeakPtrFactory<ExtensionStorageMonitor> weak_ptr_factory_;
 
-  friend class StorageEventObserver;
+  friend class SingleExtensionStorageObserver;
   friend class ExtensionStorageMonitorTest;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionStorageMonitor);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_STORAGE_MONITOR_H_