marionette.diff

diff --git a/tools/wptrunner/wptrunner/executors/executormarionette.py b/tools/wptrunner/wptrunner/executors/executormarionette.py
index ebc4a4a565..c779ea4258 100644
--- a/tools/wptrunner/wptrunner/executors/executormarionette.py
+++ b/tools/wptrunner/wptrunner/executors/executormarionette.py
@@ -46,6 +46,7 @@ from .protocol import (AccessibilityProtocolPart,
                        VirtualSensorProtocolPart,
                        DevicePostureProtocolPart,
                        VirtualPressureSourceProtocolPart,
+                       WebExtensionsProtocolPart,
                        merge_dicts)
 
 
@@ -727,6 +728,20 @@ class MarionetteVirtualPressureSourceProtocolPart(VirtualPressureSourceProtocolP
     def remove_virtual_pressure_source(self, source_type):
         raise NotImplementedError("remove_virtual_pressure_source not yet implemented")
 
+class MarionetteWebExtensionsProtocolPart(WebExtensionsProtocolPart):
+    def setup(self):
+        self.marionette = self.parent.marionette
+
+    def load_web_extension(self, extension):
+        if extension["type"] == "path" and self.parent.test_dir:
+            extension["path"] = self.parent.test_dir + extension["path"]
+
+        addons = Addons(self.marionette)
+        return addons.install(extension["path"], True)
+
+    def unload_web_extension(self, extension_id):
+        addons = Addons(self.marionette)
+        return addons.uninstall(extension_id)
 
 class MarionetteProtocol(Protocol):
     implements = [MarionetteBaseProtocolPart,
@@ -750,7 +765,8 @@ class MarionetteProtocol(Protocol):
                   MarionetteAccessibilityProtocolPart,
                   MarionetteVirtualSensorProtocolPart,
                   MarionetteDevicePostureProtocolPart,
-                  MarionetteVirtualPressureSourceProtocolPart]
+                  MarionetteVirtualPressureSourceProtocolPart,
+                  MarionetteWebExtensionsProtocolPart]
 
     def __init__(self, executor, browser, capabilities=None, timeout_multiplier=1, e10s=True, ccov=False):
         do_delayed_imports()
@@ -939,6 +955,7 @@ class MarionetteTestharnessExecutor(TestharnessExecutor):
             self.protocol.testharness.load_runner(new_environment["protocol"])
 
     def do_test(self, test):
+        self.protocol.test_dir = os.path.dirname(test.path)
         timeout = (test.timeout * self.timeout_multiplier if self.debug_info is None
                    else None)