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

chrome/browser/extensions/extension_settings_frontend.cc

 // Copyright (c) 2011 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.
 
 #include "chrome/browser/extensions/extension_settings_frontend.h"
 
 #include "base/bind.h"
 #include "base/file_path.h"
+#include "chrome/browser/extensions/extension_event_names.h"
+#include "chrome/browser/extensions/extension_event_router.h"
+#include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_settings_backend.h"
+#include "chrome/browser/profiles/profile.h"
 #include "content/browser/browser_thread.h"
 
-ExtensionSettingsFrontend::ExtensionSettingsFrontend(
-    const FilePath& base_path)
-    : core_(new ExtensionSettingsFrontend::Core()) {
+// Observer which sends events to a target profile iff the profile isn't the
+// originating profile for the event.
+class ExtensionSettingsFrontend::DefaultObserver
+    : public ExtensionSettingsObserver {
+ public:
+  explicit DefaultObserver(Profile* target_profile)
+      : target_profile_(target_profile) {}
+
+  virtual ~DefaultObserver() {}
+
+  virtual void OnSettingsChanged(
+      Profile* origin_profile,
+      const std::string& extension_id,
+      const std::string& event_json) OVERRIDE {
+    if (origin_profile != target_profile_) {
+      target_profile_->GetExtensionEventRouter()->DispatchEventToExtension(
+        extension_id,
+        extension_event_names::kOnSettingsChanged,
+        event_json,
+        target_profile_,
+        GURL());
+    }
+  }
+
+ private:
+  Profile* target_profile_;
+};
+
+// Ref-counted container for the ExtensionSettingsBackend object.
+class ExtensionSettingsFrontend::Core
+    : public base::RefCountedThreadSafe<Core> {
+ public:
+  // Constructed on UI thread.
+  explicit Core(
+      const scoped_refptr<ObserverListThreadSafe<ExtensionSettingsObserver> >&
+          observers) : observers_(observers), backend_(NULL) {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  }
+
+  // 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) {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+    DCHECK(!backend_);
+    backend_ = new ExtensionSettingsBackend(base_path, observers_);
+  }
+
+  // Runs |callback| with the extension backend.
+  void RunWithBackendOnFileThread(const BackendCallback& callback) {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+    DCHECK(backend_);
+    callback.Run(backend_);
+  }
+
+ private:
+  virtual ~Core() {
+    if (BrowserThread::CurrentlyOn(BrowserThread::FILE)) {
+      delete backend_;
+    } else if (BrowserThread::CurrentlyOn(BrowserThread::UI)) {
+      BrowserThread::DeleteSoon(BrowserThread::FILE, FROM_HERE, backend_);
+    } else {
+      NOTREACHED();
+    }
+  }
+
+  friend class base::RefCountedThreadSafe<Core>;
+
+  // Observers to settings changes (thread safe).
+  scoped_refptr<ObserverListThreadSafe<ExtensionSettingsObserver> >
+      observers_;
+
+  // Lives on the FILE thread.
+  ExtensionSettingsBackend* backend_;
+
+  DISALLOW_COPY_AND_ASSIGN(Core);
+};
+
+ExtensionSettingsFrontend::ExtensionSettingsFrontend(Profile* profile)
+    : observers_(new ObserverListThreadSafe<ExtensionSettingsObserver>()),
+      core_(new ExtensionSettingsFrontend::Core(observers_.get())) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  registrar_.Add(this, chrome::NOTIFICATION_PROFILE_CREATED,
+      NotificationService::AllBrowserContextsAndSources());
+  registrar_.Add(this, chrome::NOTIFICATION_PROFILE_DESTROYED,
+      NotificationService::AllBrowserContextsAndSources());
+  OnProfileCreated(profile);
+
   BrowserThread::PostTask(
       BrowserThread::FILE,
       FROM_HERE,
       base::Bind(
           &ExtensionSettingsFrontend::Core::InitOnFileThread,
           core_.get(),
-          base_path));
+          profile->GetPath().AppendASCII(
+              ExtensionService::kSettingsDirectoryName)));
+}
+
+ExtensionSettingsFrontend::~ExtensionSettingsFrontend() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 }
 
 void ExtensionSettingsFrontend::RunWithBackend(
     const BackendCallback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   BrowserThread::PostTask(
       BrowserThread::FILE,
       FROM_HERE,
       base::Bind(
           &ExtensionSettingsFrontend::Core::RunWithBackendOnFileThread,
           core_.get(),
           callback));
 }
 
-ExtensionSettingsFrontend::~ExtensionSettingsFrontend() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+void ExtensionSettingsFrontend::AddObserver(
+    ExtensionSettingsObserver* observer) {
+  observers_->AddObserver(observer);
 }
 
-ExtensionSettingsFrontend::Core::Core() : backend_(NULL) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+void ExtensionSettingsFrontend::RemoveObserver(
+    ExtensionSettingsObserver* observer) {
+  observers_->RemoveObserver(observer);
 }
 
-void ExtensionSettingsFrontend::Core::InitOnFileThread(
-    const FilePath& base_path) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  DCHECK(!backend_);
-  backend_ = new ExtensionSettingsBackend(base_path);
+void ExtensionSettingsFrontend::Observe(
+      int type,
+      const NotificationSource& source,
+      const NotificationDetails& details) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  switch (type) {
+    case chrome::NOTIFICATION_PROFILE_CREATED:
+      OnProfileCreated(Source<Profile>(source).ptr());
+      break;
+    case chrome::NOTIFICATION_PROFILE_DESTROYED:
+      OnProfileDestroyed(Source<Profile>(source).ptr());
+      break;
+    default:
+      NOTREACHED();
+  }
 }
 
-void ExtensionSettingsFrontend::Core::RunWithBackendOnFileThread(
-    const BackendCallback& callback) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  DCHECK(backend_);
-  callback.Run(backend_);
+void ExtensionSettingsFrontend::OnProfileCreated(Profile* new_profile) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK(profile_observers_.find(new_profile) == profile_observers_.end());
+  linked_ptr<DefaultObserver> new_observer(new DefaultObserver(new_profile));
+  profile_observers_[new_profile] = new_observer;
+  AddObserver(new_observer.get());
 }
 
-ExtensionSettingsFrontend::Core::~Core() {
-  if (BrowserThread::CurrentlyOn(BrowserThread::FILE)) {
-    delete backend_;
-  } else if (BrowserThread::CurrentlyOn(BrowserThread::UI)) {
-    BrowserThread::DeleteSoon(BrowserThread::FILE, FROM_HERE, backend_);
-  } else {
-    NOTREACHED();
-  }
+void ExtensionSettingsFrontend::OnProfileDestroyed(Profile* old_profile) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  linked_ptr<DefaultObserver> old_observer = profile_observers_[old_profile];
+  DCHECK(old_observer.get());
+  profile_observers_.erase(old_profile);
+  RemoveObserver(old_observer.get());
 }