show notification on locale change

chrome/browser/chromeos/locale_change_guard.cc

Index: chrome/browser/chromeos/locale_change_guard.cc
diff --git a/chrome/browser/chromeos/locale_change_guard.cc b/chrome/browser/chromeos/locale_change_guard.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f875cdf5745de25f8fd96c7027636f6995e23625
--- /dev/null
+++ b/chrome/browser/chromeos/locale_change_guard.cc
@@ -0,0 +1,134 @@
+// 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/chromeos/locale_change_guard.h"
+
+#include "app/l10n_util.h"
+#include "base/utf_string_conversions.h"
+#include "chrome/app/chrome_command_ids.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/metrics/user_metrics.h"
+#include "chrome/browser/prefs/pref_service.h"
+#include "chrome/browser/tab_contents/tab_contents.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/common/pref_names.h"
+#include "grit/app_resources.h"
+#include "grit/generated_resources.h"
+
+namespace {
+
+base::LazyInstance<chromeos::LocaleChangeGuard> g_locale_change_guard(
+    base::LINKER_INITIALIZED);
+
+}  // namespace
+
+namespace chromeos {
+
+LocaleChangeGuard::LocaleChangeGuard()
+    : profile_id_(Profile::InvalidProfileId),
+      tab_contents_(NULL),
+      note_(NULL),
+      reverted_(false) {
+}
+
+void LocaleChangeGuard::RevertLocaleChange(const ListValue* list) {
+  reverted_ = true;
+  UserMetrics::RecordAction(UserMetricsAction("LanguageChange_Revert"));
+  tab_contents_->profile()->ChangeApplicationLocale(from_locale_, true);
+  PrefService* prefs = tab_contents_->profile()->GetPrefs();
+  if (prefs) {
+    prefs->SetString(prefs::kApplicationLocaleBackup, from_locale_);
+    prefs->ClearPref(prefs::kApplicationLocaleAccepted);
+    prefs->ScheduleSavePersistentPrefs();
+  }
+  Browser* browser = Browser::GetBrowserForController(
+      &tab_contents_->controller(), NULL);
+  if (browser)
+    browser->ExecuteCommand(IDC_EXIT);
+}
+
+void LocaleChangeGuard::CheckLocaleChange(TabContents* tab_contents) {
+  // We want notification to be shown no more than once per session.
+  if (note_ != NULL)
+    return;
+  // We check profile Id because:
+  // (1) we want to exit fast in common case when nothing should be done.
+  // (2) on ChromeOS this guard may be invoked for a dummy profile first time.
+  ProfileId cur_profile_id = tab_contents->profile()->GetRuntimeId();
+  if (cur_profile_id == profile_id_)
+    return;
+  profile_id_ = cur_profile_id;
+  std::string cur_locale = g_browser_process->GetApplicationLocale();

[brettw, 2011/01/13 18:28:07]

I find the functions here quite hard to follow since they're just a mass of
code. Typically we would group code into a related block with a blank line
separating them and some kind of comment to make it easier to jump to what you
care about.

In this function, you're setting some class state interspersed with a whole lot
of early returns. It's not obvious that there's any ordering to this and I'm
left wondering what the state of the object should be after one of the early
returns. Can this also be better organized and documented?

In this particular case, you're checking the cur_locale against empty, but under
what cases might it be empty? It looks like it's never supposed to be empty, and
the BrowserProcess even has a DHCECK for this. If something weird will happen in
an "impossible case" then maybe there should be an assertion. In this case, I
suspect the function might even "not do something crazy" if the locale is empty.

[Denis Lagno, 2011/01/17 14:39:41]

I've created separate CL to attempt to address this:
http://codereview.chromium.org/6249009/

+  if (cur_locale.empty())
+    return;
+  PrefService* prefs = tab_contents->profile()->GetPrefs();
+  if (prefs == NULL)
+    return;
+  to_locale_ = prefs->GetString(prefs::kApplicationLocaleOverride);
+  if (!to_locale_.empty()) {
+    DCHECK(to_locale_ == cur_locale);
+    return;
+  }
+  to_locale_ = prefs->GetString(prefs::kApplicationLocale);
+  if (to_locale_ != cur_locale)
+    return;
+  from_locale_ = prefs->GetString(prefs::kApplicationLocaleBackup);
+  if (from_locale_.empty() || from_locale_ == to_locale_)
+    return;
+  note_.reset(new chromeos::SystemNotification(
+      tab_contents->profile(),
+      new Delegate(this),
+      IDR_DEFAULT_FAVICON,
+      l10n_util::GetStringUTF16(
+          IDS_OPTIONS_SETTINGS_SECTION_TITLE_LANGUAGE)));
+  tab_contents_ = tab_contents;
+  note_->Show(
+      l10n_util::GetStringFUTF16(
+          IDS_LOCALE_CHANGE_MESSAGE,
+          l10n_util::GetDisplayNameForLocale(from_locale_, to_locale_, true),
+          l10n_util::GetDisplayNameForLocale(to_locale_, to_locale_, true)),
+      l10n_util::GetStringUTF16(IDS_LOCALE_CHANGE_REVERT_MESSAGE),
+      NewCallback(this, &LocaleChangeGuard::RevertLocaleChange),
+      true,  // urgent
+      false);  // non-sticky
+}
+
+void LocaleChangeGuard::AcceptLocaleChange() {
+  // Check whether locale has been reverted or changed.
+  // If not: mark current locale as accepted.
+  if (tab_contents_ == NULL)
+    return;
+  if (reverted_)
+    return;
+  PrefService* prefs = tab_contents_->profile()->GetPrefs();
+  if (prefs == NULL)
+    return;
+  std::string override_locale =
+      prefs->GetString(prefs::kApplicationLocaleOverride);
+  if (!override_locale.empty())
+    return;
+  if (prefs->GetString(prefs::kApplicationLocale) != to_locale_)
+    return;
+  UserMetrics::RecordAction(UserMetricsAction("LanguageChange_Accept"));
+  prefs->SetString(prefs::kApplicationLocaleBackup, to_locale_);
+  prefs->SetString(prefs::kApplicationLocaleAccepted, to_locale_);
+  prefs->ScheduleSavePersistentPrefs();
+}
+
+// static
+void LocaleChangeGuard::Check(TabContents* tab_contents) {
+  g_locale_change_guard.Get().CheckLocaleChange(tab_contents);
+}
+
+void LocaleChangeGuard::Delegate::Close(bool by_user) {
+  if (by_user)
+    master_->AcceptLocaleChange();
+}
+
+std::string LocaleChangeGuard::Delegate::id() const {
+  // Arbitrary unique Id.
+  return "8c386938-1e3f-11e0-ac7b-18a90520e2e5";
+}
+
+}  // namespace chromeos