Added Tab.SnapshotContent and MapsGL example to telemetry

tools/telemetry/telemetry/tab_test_case.py

Index: tools/telemetry/telemetry/tab_test_case.py
diff --git a/tools/telemetry/telemetry/tab_test_case.py b/tools/telemetry/telemetry/tab_test_case.py
index cbd52d188c8a66ce7403d0f5d404932b43ad82ae..cd1837f41757e03aa57135685652ad4b58eeeda5 100644
--- a/tools/telemetry/telemetry/tab_test_case.py
+++ b/tools/telemetry/telemetry/tab_test_case.py
@@ -7,10 +7,19 @@ from telemetry import browser_finder
 from telemetry import options_for_unittests
 
 class TabTestCase(unittest.TestCase):
+  def __init__(self, *args):
+    self._extra_browser_args = []
+    super(TabTestCase, self).__init__(*args)
+
   def setUp(self):
     self._browser = None
     self._tab = None
     options = options_for_unittests.Get()
+
+    if self._extra_browser_args:
+      for arg in self._extra_browser_args:
+        options.extra_browser_args.append(arg)
+
     browser_to_create = browser_finder.FindBrowser(options)
     if not browser_to_create:
       raise Exception('No browser found, cannot continue test.')