Add a mouse lock test to verify bubble clear when tab focus lost.

chrome/test/functional/fullscreen_mouselock.py

Index: chrome/test/functional/fullscreen_mouselock.py
diff --git a/chrome/test/functional/fullscreen_mouselock.py b/chrome/test/functional/fullscreen_mouselock.py
index 6cc08375db997f1f6ca51c6f938b543dc640541b..beb6a4933dce9337ce62197959338429593f85dd 100755
--- a/chrome/test/functional/fullscreen_mouselock.py
+++ b/chrome/test/functional/fullscreen_mouselock.py
@@ -364,6 +364,17 @@ class FullscreenMouselockTest(pyauto.PyUITest):
     self.assertTrue(self.WaitUntil(lambda: not self.IsMouseLocked()),
                     msg='Mouse lock did not break when page is reloaded.')
 
+  def testNoMLBubbleWhenTabLoseFocus(self):
+    """Verify mouse lock bubble goes away when tab loses focus."""
+    self.NavigateToURL(self.GetHttpURLForDataPath(
+        'fullscreen_mouselock', 'fullscreen_mouselock.html'))
+    self._driver.find_element_by_id('lockMouse1').click()
+    self.assertTrue(self.WaitUntil(self.IsMouseLockPermissionRequested))
+    self.AppendTab(pyauto.GURL('chrome://newtab'))
+    self.assertTrue(self.WaitUntil(
+        lambda: not self.IsFullscreenBubbleDisplayingButtons()),
+                    msg='Mouse lock bubble did not clear when tab lost focus.')
+
   def ExitTabFSToBrowserFS(self):
     """Verify exiting tab fullscreen leaves browser in browser fullscreen.