[manifest] Remove unused manifest directory

This directory is not used.

Change-Id: I16687ce6704ecf0e9e38c82b1340cff494a90d44
diff --git a/manifest/skia b/manifest/skia
deleted file mode 100644
index 233828f..0000000
--- a/manifest/skia
+++ /dev/null
@@ -1,9 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<manifest>
-  <projects>
-    <project name="external/skia.googlesource.com/skia"
-             path="third_party/skia"
-             remote="https://skia.googlesource.com/skia"
-             revision="fe24b83bf745363c4f6bd3c22e29be4ad890cbcb"/>
-  </projects>
-</manifest>