[system health] Fix load:news:washingtonpost and browse:news:washingtonpost on Nexus9.

tools/perf/page_sets/system_health/loading_stories.py

Index: tools/perf/page_sets/system_health/loading_stories.py
diff --git a/tools/perf/page_sets/system_health/loading_stories.py b/tools/perf/page_sets/system_health/loading_stories.py
index 71ec4ff460323d4dfb4fa7d50edafc80911305ee..deb9318991c39c82094a9ccdcae0ca7f8c6bfd81 100644
--- a/tools/perf/page_sets/system_health/loading_stories.py
+++ b/tools/perf/page_sets/system_health/loading_stories.py
@@ -172,10 +172,17 @@ class LoadWashingtonPostMobileStory(_LoadingStory):
   NAME = 'load:news:washingtonpost'
   URL = 'https://www.washingtonpost.com/pwa'
   SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
+  _CLOSE_BUTTON_SELECTOR = '.close'
 
   def _DidLoadDocument(self, action_runner):
-    # Close the popup window.
-    action_runner.ClickElement(selector='.close')
+    # Close the popup window. On Nexus 9 (and probably other tables) the popup
+    # window does not have a "Close" button, instead it has only a "Send link
+    # to phone" button. So on tablets we run with the popup window open. The
+    # popup is transparent, so this is mostly an aesthetical issue.
+    has_button = action_runner.EvaluateJavaScript(
+        '!!document.querySelector("%s")' % self._CLOSE_BUTTON_SELECTOR)
+    if has_button:
+      action_runner.ClickElement(selector=self._CLOSE_BUTTON_SELECTOR)
 
 
 class LoadWikipediaStory(_LoadingStory):