Port sky_shell to Linux for testing

sky/shell/linux/platform_view_linux.cc

Index: sky/shell/linux/platform_view_linux.cc
diff --git a/sky/shell/ui_delegate.cc b/sky/shell/linux/platform_view_linux.cc
similarity index 65%
copy from sky/shell/ui_delegate.cc
copy to sky/shell/linux/platform_view_linux.cc
index e35b19243223d5231438d3d4c37722dde030956d..73fee52ab70567a4eae019d0d59b7f3f25c54dab 100644
--- a/sky/shell/ui_delegate.cc
+++ b/sky/shell/linux/platform_view_linux.cc
@@ -2,12 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "sky/shell/ui_delegate.h"
+#include "sky/shell/platform_view.h"
 
 namespace sky {
 namespace shell {
 
-UIDelegate::~UIDelegate() {
+PlatformView* PlatformView::Create(const Config& config) {
+  return new PlatformView(config);
 }
 
 }  // namespace shell