[Cast, Tests] Handle low end and JB devices that don't preload videos

chrome/test/data/android/media/simple_video.html

Index: chrome/test/data/android/media/simple_video.html
diff --git a/chrome/test/data/android/media/simple_video.html b/chrome/test/data/android/media/simple_video.html
index 7349f524db54cec23630995001557ca430beaa30..165823107153de629fbb1529ddc7d49447adb7d9 100644
--- a/chrome/test/data/android/media/simple_video.html
+++ b/chrome/test/data/android/media/simple_video.html
@@ -4,5 +4,12 @@
 <!-- Width should be large enough to dispaly all media controls without needing
 an overflow menu. -->
 <video src="test.webm" controls id="video" width=500></video>
+<script>
+function loadvideo() {
+  var video = document.getElementById('video');
+  video.load();
+}
+</script>
+<button id="button1" onclick="loadvideo()">Click me</button>
 </body>
 </html>