Extract some stuff into PackageManager

mojo/package_manager/BUILD.gn

Index: mojo/package_manager/BUILD.gn
diff --git a/chromecast/graphics/BUILD.gn b/mojo/package_manager/BUILD.gn
similarity index 54%
copy from chromecast/graphics/BUILD.gn
copy to mojo/package_manager/BUILD.gn
index f07a87154354163b625be19de5dff4c5ca38b7c9..913a36dac280104c8e2b3ee800c0f0fca143e697 100644
--- a/chromecast/graphics/BUILD.gn
+++ b/mojo/package_manager/BUILD.gn
@@ -2,15 +2,15 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source_set("graphics") {
+source_set("package_manager") {
   sources = [
-    "cast_screen.cc",
-    "cast_screen.h",
+    "package_manager_impl.cc",
+    "package_manager_impl.h",
   ]
 
   deps = [
-    "//ui/aura",
-    "//ui/gfx",
-    "//ui/gfx/geometry",
+    "//mojo/fetcher",
+    "//mojo/shell",
+    "//mojo/util:filename_util",
   ]
 }