Add SystemTrayObservers

chrome/browser/chromeos/locale_change_guard.cc

 // Copyright (c) 2012 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 "ash/shell.h"
 #include "ash/system/tray/system_tray.h"
+#include "ash/system/tray/system_tray_delegate.h"
+#include "ash/system/tray/system_tray_observers.h"
 #include "base/bind.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chromeos/settings/device_settings_service.h"
 #include "chrome/browser/notifications/notification_delegate.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_commands.h"
@@ skipping 145 matching lines @@
     return;  // Already accepted.
 
   // Locale change detected, showing notification.
   if (from_locale_ != from_locale || to_locale_ != to_locale) {
     // Falling back to showing message in current locale.
     LOG(ERROR) <<
         "Showing locale change notification in current (not previous) language";
     PrepareChangingLocale(from_locale, to_locale);
   }
 
-  if (ash::Shell::GetInstance()->status_area_widget()) {
-    ash::Shell::GetInstance()->system_tray()->locale_observer()->
-        OnLocaleChanged(this, cur_locale, from_locale_, to_locale_);
+  ash::SystemTrayObservers* observers =
+      ash::Shell::GetInstance()->tray_delegate()->GetSystemTrayObservers();

[oshima, 2012/11/09 19:21:50]

TrayDelegate has NotifyXXX methods for several other 
notifications, so it may make sense to define such methods
for these notifications as well. Yon you don't have to expose
observers and eliminate NULL check.

[sadrul, 2012/11/09 23:26:32]

I agree that it would be nice if these places all didn't have to loop over the
observer-list.

There could be TrayDelegate::NotifyXXX. Another approach would be to create a
Shell::SystemTrayProxy (or SystemTrayObserver), which is notified of these
changes. The Proxy/Observer can then iterate over the system-trays and update
their observers accordingly.

[stevenjb, 2012/11/09 23:40:45]

Yeah, I started to create NotifyXXX, but realized that most of these
could/should be moved to Ash at some point and removed from the
SystemTrayDelegate entirely.

That said, I'm OK with moving these to NotifyXXX in the meanwhile, and moving
all of NotifyXXX to SystemTrayObservers such that all of the calls look like:

ash::Shell::GetInstance()->tray_delegate()->GetSystemTrayObservers()->NotifyXXX(...)

A bit of a mouthful, but it would tidy up SystemTrayDelegate a bit. Sound
reasonable?

We could also put GetSystemTrayObservers() directly into Shell to make this less
verbose?

+  if (observers) {
+    FOR_EACH_OBSERVER(
+        ash::LocaleObserver,
+        observers->locale_observers(),
+        OnLocaleChanged(this, cur_locale, from_locale_, to_locale_));
   }
 }
 
 void LocaleChangeGuard::AcceptLocaleChange() {
   if (profile_ == NULL ||
       from_locale_.empty() ||
       to_locale_.empty()) {
     NOTREACHED();
     return;
   }
@@ skipping 41 matching lines @@
   if (by_user)
     master_->AcceptLocaleChange();
 }
 
 std::string LocaleChangeGuard::Delegate::id() const {
   // Arbitrary unique Id.
   return "8c386938-1e3f-11e0-ac7b-18a90520e2e5";
 }
 
 }  // namespace chromeos