Have mojo_shell run in its custom thread on android.

mojo/shell/ui_service_loader_android.h

+// Copyright 2014 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.
+
+#ifndef MOJO_SHELL_UI_SERVICE_LOADER_ANDROID_H_
+#define MOJO_SHELL_UI_SERVICE_LOADER_ANDROID_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "mojo/service_manager/service_loader.h"
+
+namespace mojo {
+
+class ServiceManager;
+
+namespace shell {
+class Context;
+}
+
+// ServiceLoader implementation that creates a background thread and issues load
+// requests there.
+class UIServiceLoader : public ServiceLoader {
+ public:
+  UIServiceLoader(scoped_ptr<ServiceLoader> real_loader,
+                  shell::Context* context);
+  virtual ~UIServiceLoader();
+
+  // ServiceLoader overrides:
+  virtual void LoadService(ServiceManager* manager,
+                           const GURL& url,
+                           ScopedMessagePipeHandle shell_handle) OVERRIDE;
+  virtual void OnServiceError(ServiceManager* manager,
+                              const GURL& url) OVERRIDE;
+
+ private:
+  class UILoader;
+
+  // These functions are exected on the background thread. They call through
+  // to |background_loader_| to do the actual loading.
+  // TODO: having this code take a |manager| is fragile (as ServiceManager isn't
+  // thread safe).
+  void LoadServiceOnUIThread(ServiceManager* manager,
+                             const GURL& url,
+                             ScopedMessagePipeHandle* shell_handle);
+  void OnServiceErrorOnUIThread(ServiceManager* manager, const GURL& url);
+  void ShutdownOnUIThread();
+
+  scoped_ptr<ServiceLoader> loader_;
+  shell::Context* context_;
+
+  // Lives on the UI thread. Trivial interface that calls through to |loader_|.
+  UILoader* ui_loader_;
+
+  DISALLOW_COPY_AND_ASSIGN(UIServiceLoader);
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_SHELL_UI_SERVICE_LOADER_ANDROID_H_