Implement TOGGLE_EXPANSION action for the ARC notifications.

ui/arc/notification/arc_custom_notification_view.cc

 // Copyright 2016 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 "ui/arc/notification/arc_custom_notification_view.h"
 
 #include "ash/wm/window_util.h"
 #include "base/auto_reset.h"
 #include "base/memory/ptr_util.h"
 #include "components/exo/notification_surface.h"
@@ skipping 529 matching lines @@
   }
 }
 
 views::FocusTraversable* ArcCustomNotificationView::GetFocusTraversable() {
   if (floating_control_buttons_widget_)
     return static_cast<views::internal::RootView*>(
         floating_control_buttons_widget_->GetRootView());
   return nullptr;
 }
 
+bool ArcCustomNotificationView::OnMousePressed(const ui::MouseEvent& event) {
+  // TODO(yhanada): Remove this hack as soon as possible after letting
+  // accessible actions be delivered to this view.
+  // All mouse clicks or touches should be sent to corresponding Android view
+  // because the surface is on this view, so receiving a mouse pressed event
+  // means the event is generated by automation API.
+  if (event.IsOnlyLeftMouseButton() &&
+      item_->expand_state() !=
+          message_center::NotificationExpandState::FIXED_SIZE &&
+      event.target() != surface_->window()) {
+    item_->ToggleExpansion();
+    return true;
+  }
+  return false;
+}
+
 void ArcCustomNotificationView::ButtonPressed(views::Button* sender,
                                               const ui::Event& event) {
   if (item_ && !item_->pinned() && sender == close_button_.get()) {
     CHECK_EQ(message_center::CustomNotificationView::kViewClassName,
              parent()->GetClassName());
     static_cast<message_center::CustomNotificationView*>(parent())
         ->OnCloseButtonPressed();
   }
   if (item_ && settings_button_ && sender == settings_button_) {
     item_->OpenSettings();
@@ skipping 39 matching lines @@
 
 void ArcCustomNotificationView::OnNotificationSurfaceRemoved(
     exo::NotificationSurface* surface) {
   if (surface->notification_id() != notification_key_)
     return;
 
   SetSurface(nullptr);
 }
 
 }  // namespace arc