Break dependency of native_viewport_service on mojo::shell::Context

mojo/services/native_viewport/native_viewport_service.h

Index: mojo/services/native_viewport/native_viewport_service.h
diff --git a/mojo/services/native_viewport/native_viewport_service.h b/mojo/services/native_viewport/native_viewport_service.h
index 1e6cde828a20a9ca858e25f8e026288c83544691..0a7ef42dcc5f5920267fd553a93a10959e2ad75f 100644
--- a/mojo/services/native_viewport/native_viewport_service.h
+++ b/mojo/services/native_viewport/native_viewport_service.h
@@ -10,9 +10,17 @@
 #include "mojo/services/native_viewport/native_viewport_export.h"
 #include "mojo/shell/context.h"
 
+namespace mojo {
+namespace services {
+
+class NativeViewportContext;
+
 MOJO_NATIVE_VIEWPORT_EXPORT mojo::ApplicationImpl*
     CreateNativeViewportService(
-        mojo::shell::Context* context,
-        mojo::ScopedMessagePipeHandle service_provider_handle);
+        NativeViewportContext* context,
+        ScopedMessagePipeHandle service_provider_handle);
+
+}  // namespace services
+}  // namespace mojo
 
 #endif  // MOJO_SERVICES_NATIVE_VIEWPORT_SERVICE_H_