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

tools/telemetry/telemetry/android_browser_backend.py

Index: tools/telemetry/telemetry/android_browser_backend.py
diff --git a/tools/telemetry/telemetry/android_browser_backend.py b/tools/telemetry/telemetry/android_browser_backend.py
index cc9806fcb4b0c65a8ec8252f87c31897eac41666..e3b657c7850ce69c4feb51ccb7737e1ed83ae233 100644
--- a/tools/telemetry/telemetry/android_browser_backend.py
+++ b/tools/telemetry/telemetry/android_browser_backend.py
@@ -20,6 +20,8 @@ class AndroidBrowserBackend(browser_backend.BrowserBackend):
   def __init__(self, options, adb, package,
                is_content_shell, cmdline_file, activity, devtools_remote_port):
     super(AndroidBrowserBackend, self).__init__(is_content_shell, options)
+    if len(options.extensions_to_load) > 0:
+      raise Exception('Cannot load extensions for android browser!')
     # Initialize fields so that an explosion during init doesn't break in Close.
     self._options = options
     self._adb = adb