Make PlatformViewport and NativeViewportImpl use Shell* instead of ApplicationImpl*.

services/native_viewport/platform_viewport_stub.cc

Index: services/native_viewport/platform_viewport_stub.cc
diff --git a/services/native_viewport/platform_viewport_stub.cc b/services/native_viewport/platform_viewport_stub.cc
index 081074b3c32c42e42f65f30b91767edde2c7c913..947d0b6e0d4612a599c9fe84184a04cc1afcf66c 100644
--- a/services/native_viewport/platform_viewport_stub.cc
+++ b/services/native_viewport/platform_viewport_stub.cc
@@ -7,9 +7,8 @@
 namespace mojo {
 
 // static
-scoped_ptr<PlatformViewport> PlatformViewport::Create(
-    mojo::ApplicationImpl* application_,
-    Delegate* delegate) {
+scoped_ptr<PlatformViewport> PlatformViewport::Create(mojo::Shell* shell,
+                                                      Delegate* delegate) {
   return PlatformViewportHeadless::Create(delegate);
 }