Add onChanged events to the extension settings API, both from sync and between

chrome/browser/extensions/extension_settings_frontend.h

Index: chrome/browser/extensions/extension_settings_frontend.h
diff --git a/chrome/browser/extensions/extension_settings_frontend.h b/chrome/browser/extensions/extension_settings_frontend.h
index 7fe3dc00b91ae9564be38b910b6cd4b1e2bad315..104da18ef18517efe1a1eb6e88f74f7ccf6287c2 100644
--- a/chrome/browser/extensions/extension_settings_frontend.h
+++ b/chrome/browser/extensions/extension_settings_frontend.h
@@ -6,56 +6,83 @@
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_SETTINGS_FRONTEND_H_
 #pragma once
 
+#include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
-#include "base/callback.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/observer_list_threadsafe.h"
+#include "chrome/browser/extensions/extension_settings_observer.h"
 #include "chrome/browser/sync/api/syncable_service.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
 
 class FilePath;
+class Profile;
 class ExtensionSettingsBackend;
 class ExtensionSettingsStorage;
 
 // The component of extension settings which runs on the UI thread, as opposed
 // to ExtensionSettingsBackend which lives on the FILE thread.
-class ExtensionSettingsFrontend {
+class ExtensionSettingsFrontend : public content::NotificationObserver {
  public:
-  explicit ExtensionSettingsFrontend(const FilePath& base_path);
+  explicit ExtensionSettingsFrontend(Profile* profile);
+  virtual ~ExtensionSettingsFrontend();
 
   typedef base::Callback<void(ExtensionSettingsBackend*)> BackendCallback;
 
   // Runs |callback| on the FILE thread with the extension settings.
   void RunWithBackend(const BackendCallback& callback);
 
-  ~ExtensionSettingsFrontend();
+  // Adds an observer to settings changes.
+  void AddObserver(ExtensionSettingsObserver* observer);
+
+  // Removes an observer to settings changes.
+  void RemoveObserver(ExtensionSettingsObserver* observer);
+
+  // NotificationObserver implementation.
+  virtual void Observe(
+      int type,
+      const content::NotificationSource& source,
+      const content::NotificationDetails& details) OVERRIDE;
 
  private:
-  // Ref-counted container for the ExtensionSettingsBackend object.
-  class Core : public base::RefCountedThreadSafe<Core> {
-   public:
-    // Constructed on UI thread.
-    Core();
+  // Observer which sends events to a target profile iff the profile isn't the
+  // originating profile for the event.
+  class DefaultObserver;
 
-    // Does any FILE thread specific initialization, such as construction of
-    // |backend_|.  Must be called before any call to
-    // RunWithBackendOnFileThread().
-    void InitOnFileThread(const FilePath& base_path);
+  // Called when a profile is created.
+  void OnProfileCreated(Profile* profile);
 
-    // Runs |callback| with the extension backend.
-    void RunWithBackendOnFileThread(const BackendCallback& callback);
+  // Called when a profile is destroyed.
+  void OnProfileDestroyed(Profile* profile);
 
-   private:
-    // Can be destroyed on either the UI or FILE thread.
-    virtual ~Core();
-    friend class base::RefCountedThreadSafe<Core>;
+  // Creates a scoped DefaultObserver and adds it as an Observer.
+  void SetDefaultObserver(
+      Profile* profile, scoped_ptr<DefaultObserver>* observer);
 
-    // Lives on the FILE thread.
-    ExtensionSettingsBackend* backend_;
+  // If a scoped DefaultObserver exists, clears it and removes it as an
+  // Observer.
+  void ClearDefaultObserver(scoped_ptr<DefaultObserver>* observer);
 
-    DISALLOW_COPY_AND_ASSIGN(Core);
-  };
+  // The (original) Profile this Frontend belongs to.  Note that we don't store
+  // the incognito version of the profile because it will change as it's
+  // created and destroyed during the lifetime of Chrome.
+  Profile* const profile_;
 
+  // List of observers to settings changes.
+  scoped_refptr<ObserverListThreadSafe<ExtensionSettingsObserver> > observers_;
+
+  // The default original and incognito mode profile observers.
+  scoped_ptr<DefaultObserver> original_profile_observer;
+  scoped_ptr<DefaultObserver> incognito_profile_observer_;
+
+  // Ref-counted container for the ExtensionSettingsBackend object.
+  class Core;
   scoped_refptr<Core> core_;
 
+  // For profile created/destroyed notifications.
+  content::NotificationRegistrar registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(ExtensionSettingsFrontend);
 };