Fix Chrome crashes on calling OnTrayVisibilityChange

ash/common/system/tray/system_tray_unittest.cc

Index: ash/common/system/tray/system_tray_unittest.cc
diff --git a/ash/common/system/tray/system_tray_unittest.cc b/ash/common/system/tray/system_tray_unittest.cc
index 6a9c270fc2058a587173a9288d6ebcbb172f8e0a..0eb232a7e56c0b7e89dd30c73ce826c9b4308239 100644
--- a/ash/common/system/tray/system_tray_unittest.cc
+++ b/ash/common/system/tray/system_tray_unittest.cc
@@ -60,7 +60,18 @@ class ModalWidgetDelegate : public views::WidgetDelegateView {
 
 }  // namespace
 
-typedef AshTestBase SystemTrayTest;
+class SystemTrayTest : public AshTestBase {
+ public:
+  SystemTrayTest() {}
+  ~SystemTrayTest() override {}
+
+  bool AreTraysInitialized(StatusAreaWidget* widget) {

[varkha, 2016/12/09 00:59:03]

nit: I think this could be IsWidgetInitialized().

[yiyix, 2016/12/09 20:04:53]

Done.

+    return widget->is_initialized_;
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SystemTrayTest);
+};
 
 // Verifies only the visible default views are recorded in the
 // "Ash.SystemMenu.DefaultView.VisibleItems" histogram.
@@ -664,6 +675,23 @@ TEST_F(SystemTrayTest, SystemTrayHeightWithBubble) {
 
   EXPECT_EQ(0, notification_tray->tray_bubble_height_for_test());
 }
+
+// Calling OnVisibilityChange on uninitialized |tray| caused crashes, see

[varkha, 2016/12/09 00:59:03]

nit: s/uninitialized |tray|/StatusAreaWidget that has been Shutdown

[yiyix, 2016/12/09 20:04:53]

I was not sure how to describe StatusAreaWidget that have trays uninitialized, I
like your wording.

+// crbug.com/671293. Test if crash is mitigated.
+TEST_F(SystemTrayTest, SystemTrayInitialization) {

[varkha, 2016/12/09 00:59:03]

Thanks for putting this together.

[yiyix, 2016/12/09 20:04:53]

:D

+  StatusAreaWidget* widget = StatusAreaWidgetTestHelper::GetStatusAreaWidget();
+  WebNotificationTray* notification_tray =
+      StatusAreaWidgetTestHelper::GetStatusAreaWidget()
+          ->web_notification_tray();

[varkha, 2016/12/09 00:59:03]

nit: can move this down close to the place you use it, i.e. before line 689.

[yiyix, 2016/12/09 20:04:53]

Done.

+  EXPECT_TRUE(AreTraysInitialized(widget));
+  widget->Shutdown();
+  EXPECT_FALSE(AreTraysInitialized(widget));
+  widget->OnTrayVisibilityChanged(notification_tray);
+
+  widget->CreateTrayViews();
+  EXPECT_TRUE(AreTraysInitialized(widget));
+  widget->OnTrayVisibilityChanged(notification_tray);
+}
 #endif  // OS_CHROMEOS
 
 }  // namespace test