Build fixes for latest Chromium gardening

Two repositories have been rolled into a third:
chromecast/internal/mirroring and chromecast/internal/update_engine are
now just part of chromecast/internal rather than being separate repos.

Change-Id: I0f8067ba20fff8a0cf4679a9c8e4950ceab9384c
diff --git a/default.xml b/default.xml
index c95bdcd..06dc0f8 100644
--- a/default.xml
+++ b/default.xml
@@ -35,8 +35,6 @@
   <project name="chromium/src/cast"/>
   <project name="chromium/src/chromecast/internal"/>
   <project name="chromium/src/chromecast/internal/cdm/widevine"/>
-  <project name="chromium/src/chromecast/internal/mirroring"/>
-  <project name="chromium/src/chromecast/internal/update_engine"/>
   <project name="chromium/src/chromecast/internal/vendor/fiber"/>
   <project name="chromium/src/ozone-nexus"/>
   <project name="chromium/src/sdch/open-vcdiff"/>