Add System health stories for Emerging market

tools/perf/page_sets/system_health/media_stories.py

Index: tools/perf/page_sets/system_health/media_stories.py
diff --git a/tools/perf/page_sets/system_health/media_stories.py b/tools/perf/page_sets/system_health/media_stories.py
index ad079e8d4b515282fcec217d1b9a326dc0bcc3a8..f8f907f5f560a85274d42a90853115e94a95c65c 100644
--- a/tools/perf/page_sets/system_health/media_stories.py
+++ b/tools/perf/page_sets/system_health/media_stories.py
@@ -114,3 +114,38 @@ class PandoraDesktopStory(_MediaStory):
 
   def _NavigateToMedia(self, action_runner):
     pass  # Audio autoplays on Pandora, no need to search.
+
+
+class YoutubeMobileStory(_MediaStory):
+  NAME = 'play:media:youtube'
+  URL = 'https://m.youtube.in/watch?v=OnhXkCPMeMc'
+
+  PLAYER_FUNCTION = 'document.getElementById("player")'
+  STOP_FUNCTION = 'document.getElementsByTagName("video")[0].pause()'
+  TIME_FUNCTION = 'document.getElementsByTagName("video")[0].currentTime'
+
+  def RunPageInteractions(self, action_runner):
+    platform = action_runner.tab.browser.platform
+    package = action_runner.tab.browser.GetBrowserInfo().package_name
+    action_runner.WaitForElement(element_function=self.PLAYER_FUNCTION)
+
+    # Simulate user click in system ui since youtube play can be initialied only
+    # by user gesture.
+    renderer_view = package+':id/compositor_view_holder'
+    platform.system_ui.WaitForUiNode(resource_id=renderer_view)
+    content_view = platform.system_ui.GetUiNode(resource_id=renderer_view)
+    # Click on the top half of the renderer view to start video.
+    shifted_center = 0.5 * (
+        content_view.bounds.center + content_view.bounds.top_left)
+    content_view.Tap(point=shifted_center)
+
+    self._WaitForPlayTime(action_runner)
+    action_runner.EvaluateJavaScript(self.STOP_FUNCTION)
+
+  def _GetTimeInSeconds(self, action_runner):
+    return int(action_runner.EvaluateJavaScript(self.TIME_FUNCTION))
+
+  def _NavigateToMedia(self, action_runner):
+    pass  # Audio autoplays on Pandora, no need to search.
+
+  SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY