Replace webkitpy standalone builders functions with instantiable class.

third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py

Index: third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py
diff --git a/third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py b/third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py
index bbe9eb50f9dd5c55554f0781b58d07ee2495a82c..ec00d0764a9e9426440ed2067670a58db9c71d40 100644
--- a/third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py
+++ b/third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py
@@ -32,14 +32,15 @@ from webkitpy.common.net.web_mock import MockWeb
 from webkitpy.common.system.systemhost_mock import MockSystemHost
 
 # New-style ports need to move down into webkitpy.common.
+from webkitpy.layout_tests.builders import Builders
 from webkitpy.layout_tests.port.factory import PortFactory
 from webkitpy.layout_tests.port.test import add_unit_tests_to_mock_filesystem
 
 
 class MockHost(MockSystemHost):
 
-    def __init__(self, log_executive=False, executive_throws_when_run=None, initialize_scm_by_default=True, web=None, scm=None):
-        MockSystemHost.__init__(self, log_executive, executive_throws_when_run)
+    def __init__(self, log_executive=False, executive_throws_when_run=None, initialize_scm_by_default=True, web=None, scm=None, os_name=None, os_version=None):
+        MockSystemHost.__init__(self, log_executive, executive_throws_when_run, os_name=os_name, os_version=os_version)
         add_unit_tests_to_mock_filesystem(self.filesystem)
         self.web = web or MockWeb()
 
@@ -54,6 +55,8 @@ class MockHost(MockSystemHost):
         # on the list of known ports should override this with a MockPortFactory.
         self.port_factory = PortFactory(self)
 
+        self.builders = Builders()
+
     def initialize_scm(self, patch_directories=None):
         if not self._scm:
             self._scm = MockSCM(filesystem=self.filesystem, executive=self.executive)