Proof of concept for running extension API stack through dev tools.

tools/telemetry/telemetry/browser.py

Index: tools/telemetry/telemetry/browser.py
diff --git a/tools/telemetry/telemetry/browser.py b/tools/telemetry/telemetry/browser.py
index 62e31c37b7801c80e65ad2f10c73f8f7a7bbb11a..9c9821e4b53cffdaa7d78203372b79ec6eb1f1d2 100644
--- a/tools/telemetry/telemetry/browser.py
+++ b/tools/telemetry/telemetry/browser.py
@@ -51,6 +51,10 @@ class Browser(object):
     return self._backend.supports_tab_control
 
   @property
+  def extensions(self):
+    return self._backend.extensions
+
+  @property
   def tabs(self):
     return self._backend.tabs
 
@@ -67,6 +71,12 @@ class Browser(object):
   def GetTrace(self):
     return self._backend.GetTrace()
 
+  def ConnectToExtensionPage(self, extension_id):
+    return self._backend.ConnectToExtensionPage(self, extension_id)
+
+  def ConnectToPageByUrl(self, url):
+    return self._backend.ConnectToPageByUrl(self, url)
+
   def Close(self):
     """Closes this browser."""
     if self._wpr_server: