Telemetry support for extensions.

tools/telemetry/telemetry/browser_backend.py

Index: tools/telemetry/telemetry/browser_backend.py
===================================================================
--- tools/telemetry/telemetry/browser_backend.py	(revision 178380)
+++ tools/telemetry/telemetry/browser_backend.py	(working copy)
@@ -10,6 +10,7 @@
 import sys
 
 from telemetry import browser_gone_exception
+from telemetry import extension_list_backend
 from telemetry import options_for_unittests
 from telemetry import tab_list_backend
 from telemetry import tracing_backend
@@ -44,10 +45,16 @@
                        'such as about:flags settings, cookies, and '
                        'extensions.\n')
     self._tab_list_backend = tab_list_backend.TabListBackend(self)
+    self._extension_list_backend = None
+    if not is_content_shell:
+      self._extension_list_backend = \
+          extension_list_backend.ExtensionListBackend(self)
 
   def SetBrowser(self, browser):
     self._browser = browser
     self._tab_list_backend.Init()
+    if self._extension_list_backend:
+      self._extension_list_backend.Init()
 
   @property
   def browser(self):
@@ -57,6 +64,10 @@
   def tab_list_backend(self):
     return self._tab_list_backend
 
+  @property
+  def extension_list_backend(self):
+    return self._extension_list_backend
+
   def GetBrowserStartupArgs(self):
     args = []
     args.extend(self.options.extra_browser_args)