Introduce ash mojo interface for lock screen action handlers

ash/tray_action/tray_action.cc

Index: ash/tray_action/tray_action.cc
diff --git a/ash/tray_action/tray_action.cc b/ash/tray_action/tray_action.cc
new file mode 100644
index 0000000000000000000000000000000000000000..60b9fbe107bb00533af77a042c9351922ca9bbf6
--- /dev/null
+++ b/ash/tray_action/tray_action.cc
@@ -0,0 +1,81 @@
+// 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 "ash/tray_action/tray_action.h"
+
+#include <utility>
+
+#include "ash/tray_action/tray_action_observer.h"
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/logging.h"
+
+namespace ash {
+
+TrayAction::TrayAction() = default;
+
+TrayAction::~TrayAction() = default;
+
+void TrayAction::AddObserver(TrayActionObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void TrayAction::RemoveObserver(TrayActionObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+void TrayAction::BindRequest(mojom::TrayActionRequest request) {
+  bindings_.AddBinding(this, std::move(request));
+}
+
+mojom::TrayActionState TrayAction::GetLockScreenNoteState() {
+  if (!tray_action_client_)
+    return mojom::TrayActionState::kNotSupported;
+  return lock_screen_note_state_;
+}
+
+void TrayAction::SetClient(mojom::TrayActionClientPtr tray_action_client,
+                           mojom::TrayActionState lock_screen_note_state) {
+  mojom::TrayActionState old_lock_screen_note_state = GetLockScreenNoteState();
+
+  tray_action_client_ = std::move(tray_action_client);
+
+  if (tray_action_client_) {
+    // Makes sure the state is updated in case the connection is lost.
+    tray_action_client_.set_connection_error_handler(
+        base::Bind(&TrayAction::SetClient, base::Unretained(this), nullptr,
+                   mojom::TrayActionState::kNotSupported));
+    lock_screen_note_state_ = lock_screen_note_state;
+  }
+
+  // Setting action handler value can change effective state - notify observers
+  // if that was the case.
+  if (GetLockScreenNoteState() != old_lock_screen_note_state)
+    NotifyLockScreenNoteStateChanged();
+}
+
+void TrayAction::UpdateLockScreenNoteState(mojom::TrayActionState state) {
+  if (state == lock_screen_note_state_)
+    return;
+
+  lock_screen_note_state_ = state;
+
+  // If the client is not set, the effective state has not changed, so no need
+  // to notify observers of a state change.
+  if (tray_action_client_)
+    NotifyLockScreenNoteStateChanged();
+}
+
+void TrayAction::RequestNewLockScreenNote() {
+  if (GetLockScreenNoteState() != mojom::TrayActionState::kAvailable)

[James Cook, 2017/05/05 17:22:46]

nit: you still might want to check tray_action_client_ here, since this will
crash if you request a note without a client. Or DCHECK() it at the top of the
function to be clear that it's not valid to call this without a client.

[tbarzic, 2017/05/05 17:51:17]

GetLockScreenNoteState() being kAvailable implies that tray_action_client_ is
set - added a comment and a DCHECK.

+    return;
+  tray_action_client_->RequestNewLockScreenNote();
+}
+
+void TrayAction::NotifyLockScreenNoteStateChanged() {
+  for (auto& observer : observers_)
+    observer.OnLockScreenNoteStateChanged(GetLockScreenNoteState());
+}
+
+}  // namespace ash