Fix crash in WebContentsViewAura::WindowObserver that happens when switching tabs. The exact repro …

chrome/browser/ui/webui/print_preview/print_preview_ui_browsertest.cc

 // Copyright (c) 2012 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 "base/command_line.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/content_settings/host_content_settings_map.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 123 matching lines @@
   }
 
   ASSERT_EQ(result, SIMPLEREGION);
   bool rects_equal =
       region_before.left == region_after.left &&
       region_before.top == region_after.top &&
       region_before.right == region_after.right &&
       region_before.bottom == region_after.bottom;
   ASSERT_FALSE(rects_equal);
 }
+
+IN_PROC_BROWSER_TEST_F(PrintPreviewTest, NoCrashOnCloseWithOtherTabs) {
+  // Now print preview.
+  Print();
+
+  ui_test_utils::NavigateToURLWithDisposition(
+      browser(), GURL("about:blank"), NEW_FOREGROUND_TAB,
+      ui_test_utils::BROWSER_TEST_WAIT_FOR_NAVIGATION);
+
+  browser()->tab_strip_model()->ActivateTabAt(0, true);
+
+  // Navigate main tab to hide print preview.
+  ui_test_utils::NavigateToURL(browser(), GURL("about:blank"));
+
+  browser()->tab_strip_model()->ActivateTabAt(1, true);
+}
 #endif
 
 }  // namespace