Add a simple compositor for Sky

sky/compositor/BUILD.gn

Index: sky/compositor/BUILD.gn
diff --git a/examples/ganesh_app/BUILD.gn b/sky/compositor/BUILD.gn
similarity index 59%
copy from examples/ganesh_app/BUILD.gn
copy to sky/compositor/BUILD.gn
index 3ec711792cc4ce1cde4e0bee280432bb9a5d5932..be370a8b83e841798eebd2b7864c9e75954d1924 100644
--- a/examples/ganesh_app/BUILD.gn
+++ b/sky/compositor/BUILD.gn
@@ -2,43 +2,42 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//mojo/public/mojo_application.gni")
-
-mojo_native_application("ganesh_app") {
+static_library("compositor") {
   sources = [
-    "ganesh_app.cc",
-    "ganesh_view.cc",
-    "ganesh_view.h",
-    "texture_uploader.cc",
-    "texture_uploader.h",
+    "layer.cc",
+    "layer.h",
+    "layer_client.cc",
+    "layer_client.h",
+    "layer_host.cc",
+    "layer_host.h",
+    "layer_host_client.cc",
+    "layer_host_client.h",
+    "resource_manager.cc",
+    "resource_manager.h",
+    "surface_allocator.cc",
+    "surface_allocator.h",
+    "surface_holder.cc",
+    "surface_holder.h",
   ]
 
   deps = [
     "//base",
-    "//gpu/command_buffer/client:gles2_interface",
-    "//gpu/command_buffer/common",
-    "//gpu/skia_bindings",
     "//mojo/application",
-    "//mojo/common",
     "//mojo/converters/geometry",
     "//mojo/converters/surfaces",
-    "//mojo/environment:chromium",
     "//mojo/gpu",
-    "//mojo/public/c/system:for_shared_library",
     "//mojo/public/cpp/bindings",
     "//mojo/public/cpp/environment",
     "//mojo/public/cpp/system",
     "//mojo/public/cpp/utility",
     "//mojo/public/gles2:for_shared_library",
+    "//mojo/public/interfaces/application",
     "//mojo/services/public/cpp/surfaces",
-    "//mojo/services/public/cpp/view_manager",
     "//mojo/services/public/interfaces/geometry",
-    "//mojo/services/public/interfaces/gpu",
     "//mojo/services/public/interfaces/surfaces",
     "//mojo/services/public/interfaces/surfaces:surface_id",
     "//mojo/skia",
     "//skia",
-    "//ui/gfx",
     "//ui/gfx/geometry",
   ]
 }