Add rudimentary mash shelf functionality.

mash/shell/shell_application_delegate.cc

Index: mash/shell/shell_application_delegate.cc
diff --git a/mash/shell/shell_application_delegate.cc b/mash/shell/shell_application_delegate.cc
index 11f5cb7957b60a763a60b42d1365a9f20928ea0d..6672295c3b909da5fe1c7168782134a485ee457f 100644
--- a/mash/shell/shell_application_delegate.cc
+++ b/mash/shell/shell_application_delegate.cc
@@ -20,7 +20,7 @@ void ShellApplicationDelegate::Initialize(mojo::ApplicationImpl* app) {
   StartBrowserDriver();
   StartWindowManager();
   StartWallpaper();
-  StartSystemUI();
+  StartShelf();
   StartQuickLaunch();
 }
 
@@ -42,9 +42,9 @@ void ShellApplicationDelegate::StartWallpaper() {
                                      base::Unretained(this)));
 }
 
-void ShellApplicationDelegate::StartSystemUI() {
-  StartRestartableService("mojo:system_ui",
-                          base::Bind(&ShellApplicationDelegate::StartSystemUI,
+void ShellApplicationDelegate::StartShelf() {
+  StartRestartableService("mojo:shelf",
+                          base::Bind(&ShellApplicationDelegate::StartShelf,
                                      base::Unretained(this)));
 }