Fix system tray focus cycle crash

This CL fixes the check for the message center being visible.
Also adding a unit test to cover the case that caused the crash.

Change-Id: I37b82b4d3cd08c6c8823dab0b7ddd9342a3c7673
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1857378Reviewed-by: Tim Song <tengs@chromium.org>
Commit-Queue: Ahmed Mehfooz <amehfooz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705620}

ash/system/message_center/unified_message_center_bubble.cc

@@ -93,6 +93,10 @@ bool UnifiedMessageCenterBubble::FocusOut(bool reverse) {
   return tray_->FocusQuickSettings(reverse);
 }
 
+bool UnifiedMessageCenterBubble::IsMessageCenterVisible() {
+  return message_center_view_->GetVisible();
+}
+
 TrayBackgroundView* UnifiedMessageCenterBubble::GetTray() const {
   return tray_;
 }

ash/system/message_center/unified_message_center_bubble.h

@@ -38,6 +38,9 @@ class ASH_EXPORT UnifiedMessageCenterBubble : public TrayBubbleBase,
   // Relinquish focus and transfer it to the quick settings widget.
   bool FocusOut(bool reverse);
 
+  // Returns true if notifications are shown.
+  bool IsMessageCenterVisible();
+
   // TrayBubbleBase:
   TrayBackgroundView* GetTray() const override;
   TrayBubbleView* GetBubbleView() const override;

ash/system/message_center/unified_message_center_bubble_unittest.cc

@@ -249,4 +249,36 @@ TEST_F(UnifiedMessageCenterBubbleTest, ReverseFocusCycle) {
             GetLastQuickSettingsFocusable());
 }
 
+TEST_F(UnifiedMessageCenterBubbleTest, FocusCycleWithNoNotifications) {
+  EnableMessageCenterRefactor();
+  GetPrimaryUnifiedSystemTray()->ShowBubble(true);
+
+  views::Widget* quick_settings_widget =
+      GetSystemTrayBubble()->GetBubbleWidget();
+  views::Widget* message_center_widget =
+      GetMessageCenterBubble()->GetBubbleWidget();
+
+  // First tab should focus the first element in the quick settings bubble.
+  DoTab();
+  EXPECT_TRUE(quick_settings_widget->IsActive());
+  EXPECT_FALSE(message_center_widget->IsActive());
+  EXPECT_EQ(quick_settings_widget->GetFocusManager()->GetFocusedView(),
+            GetFirstQuickSettingsFocusable());
+
+  // Keep tabbing until we reach the last focusable element in the quick
+  // settings bubble.
+  while (quick_settings_widget->GetFocusManager()->GetFocusedView() !=
+         GetLastQuickSettingsFocusable()) {
+    DoTab();
+  }
+
+  // Tab at the last element in the quick settings bubble should move focus to
+  // the first element in the quick settings bubble.
+  DoTab();
+  EXPECT_TRUE(quick_settings_widget->IsActive());
+  EXPECT_FALSE(message_center_widget->IsActive());
+  EXPECT_EQ(quick_settings_widget->GetFocusManager()->GetFocusedView(),
+            GetFirstQuickSettingsFocusable());
+}
+
 }  // namespace ash

ash/system/unified/unified_system_tray.cc

@@ -178,7 +178,7 @@ bool UnifiedSystemTray::IsSliderBubbleShown() const {
 
 bool UnifiedSystemTray::IsMessageCenterBubbleShown() const {
   if (message_center_bubble_)
-    return !!message_center_bubble_->GetBubbleWidget();
+    return message_center_bubble_->IsMessageCenterVisible();
 
   return false;
 }