Add a standalone SkyShell.apk for testing

sky/shell/sky_main.h

Index: sky/shell/sky_main.h
diff --git a/sky/compositor/rasterizer.cc b/sky/shell/sky_main.h
similarity index 52%
copy from sky/compositor/rasterizer.cc
copy to sky/shell/sky_main.h
index e0eb2d5c189c617e86582c3b774a6fa35e23af65..6913690e894700112fc9e952b670a5a8a2f01ccc 100644
--- a/sky/compositor/rasterizer.cc
+++ b/sky/shell/sky_main.h
@@ -2,14 +2,17 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "sky/compositor/rasterizer.h"
+#ifndef SKY_SHELL_SKY_MAIN_H_
+#define SKY_SHELL_SKY_MAIN_H_
 
-namespace sky {
+#include <jni.h>
 
-Rasterizer::Rasterizer() {
-}
+namespace sky {
+namespace shell {
 
-Rasterizer::~Rasterizer() {
-}
+bool RegisterSkyMain(JNIEnv* env);
 
+}  // namespace shell
 }  // namespace sky
+
+#endif  // SKY_SHELL_SKY_MAIN_H_