Fix bug in shut down of HTMLViewer

mojo/tools/data/apptests

Index: mojo/tools/data/apptests
diff --git a/mojo/tools/data/apptests b/mojo/tools/data/apptests
index 0ddb75363fc036143d1e6ed514e527f2a791793b..bf094d7c45a77cc127b03b26e21f0e117f2f17e8 100644
--- a/mojo/tools/data/apptests
+++ b/mojo/tools/data/apptests
@@ -56,24 +56,23 @@ if config.target_os != config.OS_ANDROID:
       'test': 'mojo:filesystem_apptests',
       'type': 'gtest_isolated',
     },
-# TODO(sky): reenable once 531120 is fixed.
-#    {
-#      'test': 'mojo:html_viewer_apptests',
-#      'name': 'mojo:html_viewer_apptests',
-#      'type': 'gtest_isolated',
-#      'args': ['--enable-html-viewer-test-interface',
-#               '--use-x11-test-config',
-#               '--override-use-gl-with-osmesa-for-tests']
-#    },
-#    {
-#      'test': 'mojo:html_viewer_apptests',
-#      'name': 'mojo:html_viewer_apptests new frame',
-#      'type': 'gtest_isolated',
-#      'args': ['--oopif-always-create-new-frame-tree',
-#               '--enable-html-viewer-test-interface',
-#               '--use-x11-test-config',
-#               '--override-use-gl-with-osmesa-for-tests']
-#    },
+    {
+      'test': 'mojo:html_viewer_apptests',
+      'name': 'mojo:html_viewer_apptests',
+      'type': 'gtest_isolated',
+      'args': ['--enable-html-viewer-test-interface',
+               '--use-x11-test-config',
+               '--override-use-gl-with-osmesa-for-tests']
+    },
+    {
+      'test': 'mojo:html_viewer_apptests',
+      'name': 'mojo:html_viewer_apptests new frame',
+      'type': 'gtest_isolated',
+      'args': ['--oopif-always-create-new-frame-tree',
+               '--enable-html-viewer-test-interface',
+               '--use-x11-test-config',
+               '--override-use-gl-with-osmesa-for-tests']
+    },
     # TODO(ben): These tests are disabled pending mandoline:browser refactoring.
     #{
     #  'test': 'mojo:mandoline_browser_apptests',