PreferencesManager

chrome/browser/prefs/preferences_connection_manager.cc

+// 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.
+
+#include "chrome/browser/prefs/preferences_connection_manager.h"
+
+#include "chrome/browser/prefs/preferences_manager.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/profiles/profile_manager.h"
+#include "chrome/browser/signin/profile_oauth2_token_service_factory.h"
+#include "components/keyed_service/content/browser_context_keyed_service_shutdown_notifier_factory.h"
+
+namespace {
+
+// Required singleton subclass to control dependencies between
+// PreferenceConnectionManager and the KeyedServiceShutdownNotifier.
+class ShutdownNotifierFactory
+    : public BrowserContextKeyedServiceShutdownNotifierFactory {
+ public:
+  static ShutdownNotifierFactory* GetInstance() {
+    return base::Singleton<ShutdownNotifierFactory>::get();
+  }
+
+ private:
+  friend struct base::DefaultSingletonTraits<ShutdownNotifierFactory>;
+
+  ShutdownNotifierFactory()
+      : BrowserContextKeyedServiceShutdownNotifierFactory(
+            "PreferencesConnectionManager") {
+    DependsOn(ProfileOAuth2TokenServiceFactory::GetInstance());
+  }
+  ~ShutdownNotifierFactory() override {}
+
+  DISALLOW_COPY_AND_ASSIGN(ShutdownNotifierFactory);
+};
+
+}  // namespace
+
+namespace chrome {
+
+PreferencesConnectionManager::PreferencesConnectionManager()
+    : profile_shutdown_notification_(
+          ShutdownNotifierFactory::GetInstance()
+              ->Get(ProfileManager::GetActiveUserProfile())
+              ->Subscribe(
+                  base::Bind(&PreferencesConnectionManager::OnProfileDestroyed,
+                             base::Unretained(this)))) {}

[sadrul, 2016/11/29 17:25:49]

Since you are using Unretained(this) to create the callback, do you not need to
unsubscribe from the dtor? Or does |profile_shutdown_notification_| take care of
that?

[jonross, 2016/11/30 01:01:31]

|profile_shutdown_notification_| does that deep within its dtor.

The unique_ptr + Unretained is the pattern used everywhere

+
+PreferencesConnectionManager::~PreferencesConnectionManager() {}
+
+void PreferencesConnectionManager::ProcessRequest(
+    prefs::mojom::PreferencesManagerRequest request) {
+  Profile* profile = ProfileManager::GetActiveUserProfile();
+  mojo::StrongBindingPtr<prefs::mojom::PreferencesManager> binding =
+      mojo::MakeStrongBinding(base::MakeUnique<PreferencesManager>(profile),
+                              std::move(request));
+  bindings_.push_back(binding);
+}
+
+void PreferencesConnectionManager::OnProfileDestroyed() {
+  for (auto& it : bindings_) {
+    // Check that the PreferencesManager was not cleared from a connection
+    // error.
+    if (it)
+      (static_cast<PreferencesManager*>(it->impl()))->OnProfileDestroyed();

[sadrul, 2016/11/29 17:25:49]

Not a huge fan of the static_cast<>ing. Can PreferencesManager call back into
PCM when it gets destroyed, so it updates |bindings_| instead?

[jonross, 2016/11/30 01:01:31]

This isn't for clearing out the bindings_, the StrongBindingPtr takes care of
that for us

This is for when shutdown has begun, as PrefChangeRegistrar and other parts of
the Profile code can't handle PrefService and the browser process being gone. So
I use this to clear out the listeners now.

Ideally the Profile code could handle alternative shutdown timings.

+  }
+
+  profile_shutdown_notification_.reset();
+}
+
+}  // namespace chrome