Fix for extension binding race condition when evaluating JS.

tools/telemetry/telemetry/core/extension_page.py

Index: tools/telemetry/telemetry/core/extension_page.py
diff --git a/tools/telemetry/telemetry/core/extension_page.py b/tools/telemetry/telemetry/core/extension_page.py
index 0ca5d2941511b74f12205d5bbdd92a1e1a6675d7..3402878b61102d809d3251b2f6b67506f6fe004e 100644
--- a/tools/telemetry/telemetry/core/extension_page.py
+++ b/tools/telemetry/telemetry/core/extension_page.py
@@ -5,8 +5,18 @@ from telemetry.core import web_contents
 
 class ExtensionPage(web_contents.WebContents):
   """Represents a an extension page in the browser"""
-  def __init__(self, inspector_backend):
+  def __init__(self, extension_id, url, inspector_backend):
     super(ExtensionPage, self).__init__(inspector_backend)
+    self.extension_id = extension_id
+    self.url = url
+    assert url.startswith('chrome-extension://' + extension_id)
 
   def __del__(self):
     super(ExtensionPage, self).__del__()
+
+  def Reload(self):
+    """ Reloading an extension page is used as a workaround for an extension
+    binding bug for old versions of Chrome (crbug.com/263162). After Navigate
+    returns, we are guaranteed that the inspected page is in the correct state.
+    """
+    self._inspector_backend.Navigate(self.url, None, 10)