Move shell interfaces into the shell.mojom namespace.

components/html_viewer/html_viewer.cc

Index: components/html_viewer/html_viewer.cc
diff --git a/components/html_viewer/html_viewer.cc b/components/html_viewer/html_viewer.cc
index 0b59fe39ac16eac7993c0eedc80bb8d97cd6f537..e133ea171488223bbe6329e5b14ef4a0d30b9025 100644
--- a/components/html_viewer/html_viewer.cc
+++ b/components/html_viewer/html_viewer.cc
@@ -31,7 +31,7 @@ bool HTMLViewer::AcceptConnection(
 
 void HTMLViewer::Create(
     mojo::ApplicationConnection* connection,
-    mojo::InterfaceRequest<mojo::ContentHandler> request) {
+    mojo::InterfaceRequest<mojo::shell::mojom::ContentHandler> request) {
   new ContentHandlerImpl(global_state_.get(), app_, std::move(request));
 }