Allow chromedriver to install an extension and get all installed extension IDs.

chrome/test/functional/execute_javascript.py

Index: chrome/test/functional/execute_javascript.py
diff --git a/chrome/test/functional/execute_javascript.py b/chrome/test/functional/execute_javascript.py
index b935a5139874deb84f4c3ede182c9da81df368a4..835bf6cb6edc9cbff99e7e4b9e6f2f3455e35a69 100644
--- a/chrome/test/functional/execute_javascript.py
+++ b/chrome/test/functional/execute_javascript.py
@@ -37,8 +37,7 @@ class ExecuteJavascriptTest(PyUITest):
     """Test we can inject JavaScript into an extension."""
     dir_path = os.path.abspath(
         os.path.join(self.DataDir(), 'extensions', 'js_injection_background'))
-    ext_id = self.InstallExtension(dir_path, False);
-    self.assertTrue(ext_id, msg='Failed to install extension: %s.' % dir_path)
+    ext_id = self.InstallExtension(dir_path)
 
     # Verify extension is enabled.
     extension = self._GetExtensionInfoById(self.GetExtensionsInfo(), ext_id)