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

chrome/browser/chromeos/input_method/input_method_persistence.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/input_method_persistence.h"
+
+#include "base/logging.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/chromeos/input_method/input_method_util.h"
+#include "chrome/browser/chromeos/language_preferences.h"
+#include "chrome/browser/prefs/pref_service.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/profiles/profile_manager.h"
+#include "chrome/common/pref_names.h"
+
+namespace chromeos {
+namespace input_method {
+namespace {
+
+void PersistSystemInputMethod(const std::string& input_method) {
+  PrefServiceBase* local_state = NULL;
+  if (g_browser_process)
+    local_state = g_browser_process->local_state();
+  DCHECK(local_state);
+
+  if (local_state) {

[Seigo Nonaka, 2012/12/11 04:33:04]

You check the |local_state| just above.

Plz remove this condition or just
if (!local_state)
  return;
is fine, I think.

[erikwright (departed), 2012/12/11 16:39:44]

Done. Note that the original code did DCHECK in this condition.

See the removal in the current CL:
https://codereview.chromium.org/11466010/diff/22001/chrome/browser/chromeos/i...

And it originated from BrowserStateMonitor - see removal in a prior CL (line
70):
https://codereview.chromium.org/11415266/diff/25001/chrome/browser/chromeos/i...

But I don't see big value in DCHECKing here at this point.

+    local_state->SetString(
+        language_prefs::kPreferredKeyboardLayout, input_method);
+  }
+}
+
+void PersistUserInputMethod(const std::string& input_method) {
+  PrefServiceBase* user_prefs = NULL;
+  Profile* profile = ProfileManager::GetDefaultProfile();
+  if (profile)
+    user_prefs = profile->GetPrefs();
+  if (!user_prefs)
+    return;
+
+  const std::string current_input_method_on_pref =
+      user_prefs->GetString(prefs::kLanguageCurrentInputMethod);
+  if (current_input_method_on_pref == input_method)
+    return;
+
+  user_prefs->SetString(prefs::kLanguagePreviousInputMethod,
+                        current_input_method_on_pref);
+  user_prefs->SetString(prefs::kLanguageCurrentInputMethod,
+                        input_method);
+}
+
+}  // namespace
+
+InputMethodPersistence::InputMethodPersistence(
+    InputMethodManager* input_method_manager)
+    : input_method_manager_(input_method_manager),
+      state_(InputMethodManager::STATE_LOGIN_SCREEN) {
+  input_method_manager_->AddObserver(this);
+}
+
+InputMethodPersistence::~InputMethodPersistence() {
+  input_method_manager_->RemoveObserver(this);
+}
+
+void InputMethodPersistence::InputMethodChanged(
+    InputMethodManager* manager, bool show_message) {
+  DCHECK_EQ(input_method_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;
+      }
+      PersistSystemInputMethod(current_input_method);
+      return;
+    case InputMethodManager::STATE_BROWSER_SCREEN:
+      PersistUserInputMethod(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 InputMethodPersistence::InputMethodPropertyChanged(
+    InputMethodManager* manager) {}
+
+void InputMethodPersistence::OnSessionStateChange(
+    InputMethodManager::State new_state) {
+  state_ = new_state;
+}
+
+}  // namespace input_method
+}  // namespace chromeos