chrome.settingsPrivate: Implement onPrefsChanged event handling.

chrome/browser/extensions/api/settings_private/settings_private_event_router.cc

+// Copyright 2015 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/api/settings_private/settings_private_event_router.h"
+
+#include <vector>
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/prefs/pref_service.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/extensions/api/settings_private/prefs_util.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/common/extensions/api/settings_private.h"
+#include "content/public/browser/browser_context.h"
+
+namespace extensions {
+
+SettingsPrivateEventRouter::SettingsPrivateEventRouter(
+    content::BrowserContext* context)
+    : context_(context), listening_(false) {
+  // Register with the event router so we know when renderers are listening to
+  // our events. We first check and see if there *is* an event router, because
+  // some unit tests try to create all context services, but don't initialize
+  // the event router first.
+  EventRouter* event_router = EventRouter::Get(context_);
+  if (event_router) {
+    event_router->RegisterObserver(
+        this, api::settings_private::OnPrefsChanged::kEventName);
+    StartOrStopListeningForPrefsChanges();
+  }
+
+  Profile* profile = Profile::FromBrowserContext(context_);
+  user_prefs_registrar_.Init(profile->GetPrefs());
+  local_state_registrar_.Init(g_browser_process->local_state());
+}
+
+SettingsPrivateEventRouter::~SettingsPrivateEventRouter() {
+  DCHECK(!listening_);
+}
+
+void SettingsPrivateEventRouter::Shutdown() {
+  // Unregister with the event router. We first check and see if there *is* an
+  // event router, because some unit tests try to shutdown all context services,
+  // but didn't initialize the event router first.
+  EventRouter* event_router = EventRouter::Get(context_);
+  if (event_router)
+    event_router->UnregisterObserver(this);
+
+  if (listening_) {
+    const prefs_util::TypedPrefMap& keys = prefs_util::GetWhitelistedKeys();
+    for (const auto& it : keys) {
+      FindRegistrarForPref(it.first)->Remove(it.first);
+    }
+  }
+  listening_ = false;
+}
+
+void SettingsPrivateEventRouter::OnListenerAdded(
+    const EventListenerInfo& details) {
+  // Start listening to events from the PrefChangeRegistrars.
+  StartOrStopListeningForPrefsChanges();
+}
+
+void SettingsPrivateEventRouter::OnListenerRemoved(
+    const EventListenerInfo& details) {
+  // Stop listening to events from the PrefChangeRegistrars if there are no
+  // more listeners.
+  StartOrStopListeningForPrefsChanges();
+}
+
+PrefChangeRegistrar* SettingsPrivateEventRouter::FindRegistrarForPref(
+    const std::string& pref_name) {
+  Profile* profile = Profile::FromBrowserContext(context_);
+  if (prefs_util::FindServiceForPref(profile, pref_name) ==
+      profile->GetPrefs()) {
+    return &user_prefs_registrar_;
+  }
+  return &local_state_registrar_;
+}
+
+void SettingsPrivateEventRouter::StartOrStopListeningForPrefsChanges() {
+  EventRouter* event_router = EventRouter::Get(context_);
+  bool should_listen = event_router->HasEventListener(
+      api::settings_private::OnPrefsChanged::kEventName);
+
+  if (should_listen && !listening_) {
+    const prefs_util::TypedPrefMap& keys = prefs_util::GetWhitelistedKeys();
+    for (const auto& it : keys) {
+      FindRegistrarForPref(it.first)->Add(
+          it.first,
+          base::Bind(&SettingsPrivateEventRouter::OnPreferenceChanged,
+                     base::Unretained(this), user_prefs_registrar_.prefs()));
+    }
+  } else if (!should_listen && listening_) {
+    const prefs_util::TypedPrefMap& keys = prefs_util::GetWhitelistedKeys();
+    for (const auto& it : keys) {
+      FindRegistrarForPref(it.first)->Remove(it.first);
+    }
+  }
+  listening_ = should_listen;
+}
+
+void SettingsPrivateEventRouter::OnPreferenceChanged(
+    PrefService* service,
+    const std::string& pref_name) {
+  EventRouter* event_router = EventRouter::Get(context_);
+  if (!event_router->HasEventListener(
+          api::settings_private::OnPrefsChanged::kEventName)) {
+    return;
+  }
+
+  Profile* profile = Profile::FromBrowserContext(context_);
+  api::settings_private::PrefObject* pref_object =
+      prefs_util::GetPref(profile, pref_name).release();
+
+  std::vector<linked_ptr<api::settings_private::PrefObject>> prefs;
+  prefs.push_back(linked_ptr<api::settings_private::PrefObject>(pref_object));
+
+  scoped_ptr<base::ListValue> args(
+      api::settings_private::OnPrefsChanged::Create(prefs));
+
+  scoped_ptr<Event> extension_event(new Event(
+      api::settings_private::OnPrefsChanged::kEventName, args.Pass()));
+  event_router->BroadcastEvent(extension_event.Pass());
+}
+
+SettingsPrivateEventRouter* SettingsPrivateEventRouter::Create(
+    content::BrowserContext* context) {
+  return new SettingsPrivateEventRouter(context);
+}
+
+}  // namespace extensions