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

tools/telemetry/telemetry/browser_options.py

Index: tools/telemetry/telemetry/browser_options.py
diff --git a/tools/telemetry/telemetry/browser_options.py b/tools/telemetry/telemetry/browser_options.py
index be52f17b1174eecb1e994567fe40388cf052256e..daf68e898d7d3e00bd62280d930121b12ae72bbf 100644
--- a/tools/telemetry/telemetry/browser_options.py
+++ b/tools/telemetry/telemetry/browser_options.py
@@ -10,6 +10,11 @@ import copy
 from telemetry import browser_finder
 from telemetry import wpr_modes
 
+class ExtensionToLoad(object):
+  def __init__(self, path, is_component):
+    self.path = path
+    self.is_component = is_component
+
 class BrowserOptions(optparse.Values):
   """Options to be used for discovering and launching a browser."""
 
@@ -25,6 +30,7 @@ class BrowserOptions(optparse.Values):
     self.dont_override_profile = False
     self.extra_browser_args = []
     self.show_stdout = False
+    self.extensions_to_load = []
 
     self.cros_remote = None
     self.wpr_mode = wpr_modes.WPR_OFF
@@ -81,6 +87,12 @@ class BrowserOptions(optparse.Values):
     group.add_option('--show-stdout',
         action='store_true',
         help='When possible, will display the stdout of the process')
+    group.add_option('--load-component-extension',
+        dest='component_extensions_to_load_as_string',
+        help='Loads additional component extensions.')
+    group.add_option('--load-extension',
+        dest='extensions_to_load_as_string',
+        help='Loads additional extension.')
     parser.add_option_group(group)
 
     # Page set options
@@ -142,6 +154,18 @@ class BrowserOptions(optparse.Values):
           self.extra_browser_args_as_string) # pylint: disable=E1101
         self.extra_browser_args.extend(tmp)
         delattr(self, 'extra_browser_args_as_string')
+      if self.component_extensions_to_load_as_string: # pylint: disable=E1101
+        paths = self.component_extensions_to_load_as_string.split(',')
+        self.extensions_to_load.extend(
+            [ExtensionToLoad(ext_path, True)
+             for ext_path in paths])
+        delattr(self, 'component_extensions_to_load_as_string')
+      if self.extensions_to_load_as_string: # pylint: disable=E1101
+        paths = self.extensions_to_load_as_string.split(',')
+        self.extensions_to_load.extend(
+            [ExtensionToLoad(ext_path, False)
+             for ext_path in paths])
+        delattr(self, 'component_extensions_to_load_as_string')
       return ret
     parser.parse_args = ParseArgs
     return parser