[webkitpy] Merge ChromiumBuildBot class into the BuildBot class.

Tools/Scripts/webkitpy/common/host_mock.py

Index: Tools/Scripts/webkitpy/common/host_mock.py
diff --git a/Tools/Scripts/webkitpy/common/host_mock.py b/Tools/Scripts/webkitpy/common/host_mock.py
index 0a6497acaebb0b66cc46ef58cdb5f9e0eba13ad3..b51eea6e9433e705cd68a10bd1b247d01933fa0d 100644
--- a/Tools/Scripts/webkitpy/common/host_mock.py
+++ b/Tools/Scripts/webkitpy/common/host_mock.py
@@ -48,7 +48,6 @@ class MockHost(MockSystemHost):
         if initialize_scm_by_default:
             self.initialize_scm()
         self.buildbot = MockBuildBot()
-        self._chromium_buildbot = MockBuildBot()
 
         # Note: We're using a real PortFactory here.  Tests which don't wish to depend
         # on the list of known ports should override this with a MockPortFactory.
@@ -71,6 +70,3 @@ class MockHost(MockSystemHost):
 
     def checkout(self):
         return self._checkout
-
-    def chromium_buildbot(self):
-        return self._chromium_buildbot