Introduce lock_screen_apps to chrome/browser/chromeos

chrome/browser/chromeos/lock_screen_apps/state_controller.cc

+// Copyright 2017 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/lock_screen_apps/state_controller.h"
+
+#include "base/bind.h"
+#include "base/command_line.h"
+#include "base/location.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "base/time/time.h"
+#include "chromeos/chromeos_switches.h"
+
+namespace lock_screen_apps {
+
+namespace {
+
+base::LazyInstance<StateController>::Leaky g_instance =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+// static
+StateController* StateController::Get() {
+  if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
+          chromeos::switches::kEnableLockScreenApps)) {
+    return nullptr;
+  }
+  return g_instance.Pointer();
+}
+
+void StateController::AddObserver(StateObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void StateController::RemoveObserver(StateObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+ActionState StateController::GetActionState(Action action) const {
+  DCHECK_EQ(Action::kNewNote, action);
+  return new_note_state_;
+}
+
+bool StateController::HandleAction(Action action) {
+  DCHECK_EQ(Action::kNewNote, action);
+
+  if (new_note_state_ != ActionState::kAvailable &&
+      new_note_state_ != ActionState::kHidden) {
+    return false;
+  }
+
+  // TODO(tbarzic): Implement this.
+  NOTIMPLEMENTED();
+  return true;
+}
+
+void StateController::MoveToBackground() {
+  UpdateActionState(Action::kNewNote, ActionState::kHidden);
+}
+
+StateController::StateController() {}
+
+StateController::~StateController() {}
+
+bool StateController::UpdateActionState(Action action,
+                                        ActionState action_state) {
+  DCHECK_EQ(Action::kNewNote, action);
+
+  const ActionState kOldState = GetActionState(action);

[jdufault, 2017/05/02 20:16:02]

kOldState => old_state? I don't think constant style naming applies because
kOldState varies throughout program execution.

[tbarzic, 2017/05/02 20:20:11]

Done.

+  if (kOldState == action_state)
+    return false;
+
+  if (action_state == ActionState::kHidden && kOldState != ActionState::kActive)
+    return false;
+
+  new_note_state_ = action_state;
+  NotifyStateChanged(Action::kNewNote);
+  return true;
+}
+
+void StateController::NotifyStateChanged(Action action) {
+  DCHECK_EQ(Action::kNewNote, action);
+
+  for (auto& observer : observers_)
+    observer.OnLockScreenAppsStateChanged(Action::kNewNote, new_note_state_);
+}
+
+}  // namespace lock_screen_apps