ash/mash: Add a mus-client that sets up ash to provide the system ui for mash.

mash/shell/shell_application_delegate.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mash/shell/shell_application_delegate.h"
 
 #include "base/bind.h"
+#include "base/command_line.h"
 #include "mojo/shell/public/cpp/connection.h"
 #include "mojo/shell/public/cpp/shell.h"
 
+namespace {
+
+const char kUseAshSysui[] = "use-ash-sysui";
+
+}  // namespace
+
 namespace mash {
 namespace shell {
 
 ShellApplicationDelegate::ShellApplicationDelegate()
     : shell_(nullptr), screen_locked_(false) {}
 
 ShellApplicationDelegate::~ShellApplicationDelegate() {}
 
 void ShellApplicationDelegate::Initialize(mojo::Shell* shell,
                                           const std::string& url,
                                           uint32_t id) {
   shell_ = shell;
   StartBrowserDriver();
   StartWindowManager();
-  StartWallpaper();
-  StartShelf();
+  StartSystemUI();
   StartQuickLaunch();
 }
 
 bool ShellApplicationDelegate::AcceptConnection(mojo::Connection* connection) {
   connection->AddInterface<mash::shell::mojom::Shell>(this);
   return true;
 }
 
 void ShellApplicationDelegate::AddScreenlockStateListener(
     mojom::ScreenlockStateListenerPtr listener) {
@@ skipping 28 matching lines @@
   bindings_.AddBinding(this, std::move(r));
 }
 
 void ShellApplicationDelegate::StartWindowManager() {
   StartRestartableService(
       "mojo:desktop_wm",
       base::Bind(&ShellApplicationDelegate::StartWindowManager,
                  base::Unretained(this)));
 }
 
+void ShellApplicationDelegate::StartSystemUI() {
+  static bool use_ash =
+      base::CommandLine::ForCurrentProcess()->HasSwitch(kUseAshSysui);
+  if (use_ash) {
+    StartRestartableService("mojo:ash_sysui",
+                            base::Bind(&ShellApplicationDelegate::StartSystemUI,
+                                       base::Unretained(this)));
+  } else {
+    StartWallpaper();
+    StartShelf();
+  }
+}
+
 void ShellApplicationDelegate::StartWallpaper() {
   StartRestartableService("mojo:wallpaper",
                           base::Bind(&ShellApplicationDelegate::StartWallpaper,
                                      base::Unretained(this)));
 }
 
 void ShellApplicationDelegate::StartShelf() {
   StartRestartableService("mojo:shelf",
                           base::Bind(&ShellApplicationDelegate::StartShelf,
                                      base::Unretained(this)));
@@ skipping 35 matching lines @@
   // Note: |connection| may be null if we've lost our connection to the shell.
   if (connection) {
     connection->SetRemoteServiceProviderConnectionErrorHandler(
         restart_callback);
     connections_[url] = std::move(connection);
   }
 }
 
 }  // namespace shell
 }  // namespace main