Unified: Fix user chooser minor issues.

This CL fixes two issues related to UserChooserView in
UnifiedSystemTray.
* Ensure the UnifiedSystemTray bubble is expanded before showing
  UserChooserView.
* Show error messages when number of added users reaches the limit.

BUG=890720,890722
TEST=manual

Change-Id: I2ea7c807da18e165f66345e50b9c6cf39e954840
Reviewed-on: https://chromium-review.googlesource.com/1255745Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595760}

ash/system/unified/unified_system_tray_controller.cc

@@ -229,6 +229,8 @@ void UnifiedSystemTrayController::Fling(int velocity) {
 void UnifiedSystemTrayController::ShowUserChooserView() {
   if (!IsUserChooserEnabled())
     return;
+  animation_->Reset(1.0);
+  UpdateExpandedAmount();
   unified_view_->SetDetailedView(new UserChooserView(this));
 }
 

ash/system/unified/user_chooser_view.cc

@@ -120,6 +120,18 @@ class Separator : public views::View {
   DISALLOW_COPY_AND_ASSIGN(Separator);
 };
 
+views::View* CreateAddUserErrorView(const base::string16& message) {
+  auto* label = new views::Label(message);
+  label->SetEnabledColor(kUnifiedMenuTextColor);
+  label->SetAutoColorReadabilityEnabled(false);
+  label->SetSubpixelRenderingEnabled(false);
+  label->SetBorder(
+      views::CreateEmptyBorder(gfx::Insets(kUnifiedTopShortcutSpacing)));
+  label->SetMultiLine(true);
+  label->SetHorizontalAlignment(gfx::HorizontalAlignment::ALIGN_LEFT);
+  return label;
+}
+
 }  // namespace
 
 views::View* CreateUserAvatarView(int user_index) {
@@ -257,9 +269,24 @@ UserChooserView::UserChooserView(UnifiedSystemTrayController* controller) {
     AddChildView(button);
     AddChildView(new Separator(i < num_users - 1));
   }
-  if (Shell::Get()->session_controller()->GetAddUserPolicy() ==
-      AddUserSessionPolicy::ALLOWED) {
-    AddChildView(new AddUserButton(controller));
+
+  switch (Shell::Get()->session_controller()->GetAddUserPolicy()) {
+    case AddUserSessionPolicy::ALLOWED:
+      AddChildView(new AddUserButton(controller));
+      break;
+    case AddUserSessionPolicy::ERROR_NOT_ALLOWED_PRIMARY_USER:
+      AddChildView(CreateAddUserErrorView(l10n_util::GetStringUTF16(
+          IDS_ASH_STATUS_TRAY_MESSAGE_NOT_ALLOWED_PRIMARY_USER)));
+      break;
+    case AddUserSessionPolicy::ERROR_MAXIMUM_USERS_REACHED:
+      AddChildView(CreateAddUserErrorView(l10n_util::GetStringFUTF16Int(
+          IDS_ASH_STATUS_TRAY_MESSAGE_CANNOT_ADD_USER,
+          session_manager::kMaximumNumberOfUserSessions)));
+      break;
+    case AddUserSessionPolicy::ERROR_NO_ELIGIBLE_USERS:
+      AddChildView(CreateAddUserErrorView(
+          l10n_util::GetStringUTF16(IDS_ASH_STATUS_TRAY_MESSAGE_OUT_OF_USERS)));
+      break;
   }
 
   Shell::Get()->media_controller()->AddObserver(this);