Decompose BrowserStateMonitor into two parts, simplifying unit tests and APIs.

chrome/browser/chromeos/input_method/browser_state_monitor.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/input_method/browser_state_monitor.h"
 
 #include "base/logging.h"
 #include "chrome/browser/chromeos/input_method/input_method_delegate.h"
 #include "chrome/browser/chromeos/input_method/input_method_util.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "content/public/browser/notification_service.h"
 
 namespace chromeos {
 namespace input_method {
 
-BrowserStateMonitor::BrowserStateMonitor(InputMethodManager* manager,
-                                         InputMethodDelegate* delegate)
-    : manager_(manager),
-      delegate_(delegate),
+BrowserStateMonitor::BrowserStateMonitor(
+    const base::Callback<void(InputMethodManager::State)>& observer)
+    : observer_(observer),
       state_(InputMethodManager::STATE_LOGIN_SCREEN) {
   notification_registrar_.Add(this,
                               chrome::NOTIFICATION_LOGIN_USER_CHANGED,
                               content::NotificationService::AllSources());
   notification_registrar_.Add(this,
                               chrome::NOTIFICATION_SESSION_STARTED,
                               content::NotificationService::AllSources());
   notification_registrar_.Add(this,
                               chrome::NOTIFICATION_SCREEN_LOCK_STATE_CHANGED,
                               content::NotificationService::AllSources());
   // We should not use ALL_BROWSERS_CLOSING here since logout might be cancelled
   // by JavaScript after ALL_BROWSERS_CLOSING is sent (crosbug.com/11055).
   notification_registrar_.Add(this,
                               chrome::NOTIFICATION_APP_TERMINATING,
                               content::NotificationService::AllSources());
 
-  manager_->SetState(state_);
-  manager_->AddObserver(this);
+  observer.Run(state_);

[Seigo Nonaka, 2012/12/11 17:01:52]

nit: please add null check here too.

 }
 
 BrowserStateMonitor::~BrowserStateMonitor() {
-  manager_->RemoveObserver(this);
 }
 
-void BrowserStateMonitor::InputMethodChanged(InputMethodManager* manager,
-                                             bool show_message) {
-  DCHECK_EQ(manager_, manager);
-  const std::string current_input_method =
-      manager->GetCurrentInputMethod().id();
-  // Save the new input method id depending on the current browser state.
-  switch (state_) {
-    case InputMethodManager::STATE_LOGIN_SCREEN:
-      if (!InputMethodUtil::IsKeyboardLayout(current_input_method)) {
-        DVLOG(1) << "Only keyboard layouts are supported: "
-                 << current_input_method;
-        return;
-      }
-      delegate_->SetSystemInputMethod(current_input_method);
-      return;
-    case InputMethodManager::STATE_BROWSER_SCREEN:
-      delegate_->SetUserInputMethod(current_input_method);
-      return;
-    case InputMethodManager::STATE_LOCK_SCREEN:
-      // We use a special set of input methods on the screen. Do not update.
-      return;
-    case InputMethodManager::STATE_TERMINATING:
-      return;
-  }
-  NOTREACHED();
-}
-
-void BrowserStateMonitor::InputMethodPropertyChanged(
-    InputMethodManager* manager) {}
-
 void BrowserStateMonitor::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
+  const InputMethodManager::State old_state = state_;
   switch (type) {
     case chrome::NOTIFICATION_APP_TERMINATING: {
-      SetState(InputMethodManager::STATE_TERMINATING);
+      state_ = InputMethodManager::STATE_TERMINATING;
       break;
     }
     case chrome::NOTIFICATION_LOGIN_USER_CHANGED: {
       // The user logged in, but the browser window for user session is not yet
       // ready. An initial input method hasn't been set to the manager.
       // Note that the notification is also sent when Chrome crashes/restarts
       // as of writing, but it might be changed in the future (therefore we need
       // to listen to NOTIFICATION_SESSION_STARTED as well.)
       DVLOG(1) << "Received chrome::NOTIFICATION_LOGIN_USER_CHANGED";
-      SetState(InputMethodManager::STATE_BROWSER_SCREEN);
+      state_ = InputMethodManager::STATE_BROWSER_SCREEN;
       break;
     }
     case chrome::NOTIFICATION_SESSION_STARTED: {
       // The user logged in, and the browser window for user session is ready.
       // An initial input method has already been set.
       // We should NOT call InitializePrefMembers() here since the notification
       // is sent in the PreProfileInit phase in case when Chrome crashes and
       // restarts.
       DVLOG(1) << "Received chrome::NOTIFICATION_SESSION_STARTED";
-      SetState(InputMethodManager::STATE_BROWSER_SCREEN);
+      state_ = InputMethodManager::STATE_BROWSER_SCREEN;
       break;
     }
     case chrome::NOTIFICATION_SCREEN_LOCK_STATE_CHANGED: {
       const bool is_screen_locked = *content::Details<bool>(details).ptr();
-      SetState(is_screen_locked ? InputMethodManager::STATE_LOCK_SCREEN :
-               InputMethodManager::STATE_BROWSER_SCREEN);
+      state_ = is_screen_locked ? InputMethodManager::STATE_LOCK_SCREEN :
+          InputMethodManager::STATE_BROWSER_SCREEN;
       break;
     }
     default: {
       NOTREACHED();
       break;
     }
   }
+
+  if (old_state != state_ && !observer_.is_null())
+    observer_.Run(state_);
+
   // Note: browser notifications are sent in the following order.
   //
   // Normal login:
   // 1. chrome::NOTIFICATION_LOGIN_USER_CHANGED is sent.
   // 2. Preferences::NotifyPrefChanged() is called. preload_engines (which
   //    might change the current input method) and current/previous input method
   //    are sent to the manager.
   // 3. chrome::NOTIFICATION_SESSION_STARTED is sent.
   //
   // Chrome crash/restart (after logging in):
   // 1. chrome::NOTIFICATION_LOGIN_USER_CHANGED might be sent.
   // 2. chrome::NOTIFICATION_SESSION_STARTED is sent.
   // 3. Preferences::NotifyPrefChanged() is called. The same things as above
   //    happen.
   //
   // We have to be careful not to overwrite both local and user prefs when
   // preloaded engine is set. Note that it does not work to do nothing in
   // InputMethodChanged() between chrome::NOTIFICATION_LOGIN_USER_CHANGED and
   // chrome::NOTIFICATION_SESSION_STARTED because SESSION_STARTED is sent very
   // early on Chrome crash/restart.
 }
 
-void BrowserStateMonitor::SetState(InputMethodManager::State new_state) {
-  const InputMethodManager::State old_state = state_;
-  state_ = new_state;
-  if (old_state != state_)
-    manager_->SetState(state_);
-}
-
 }  // namespace input_method
 }  // namespace chromeos