Add some |using mojo::...;|s to //shell .cc files.

shell/test/pingable_app.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 "mojo/public/c/system/main.h"
 #include "mojo/public/cpp/application/application_delegate.h"
 #include "mojo/public/cpp/application/application_impl.h"
 #include "mojo/public/cpp/application/application_runner.h"
 #include "mojo/public/cpp/application/interface_factory.h"
 #include "mojo/public/cpp/bindings/callback.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "mojo/public/cpp/bindings/strong_binding.h"
 #include "shell/test/pingable.mojom.h"
 
+using mojo::String;
+
 class PingableImpl : public Pingable {
  public:
   PingableImpl(mojo::InterfaceRequest<Pingable> request,
                const std::string& app_url,
                const std::string& connection_url)
       : binding_(this, request.Pass()),
         app_url_(app_url),
         connection_url_(connection_url) {}
 
   ~PingableImpl() override {}
 
  private:
   void Ping(
-      const mojo::String& message,
-      const mojo::Callback<void(mojo::String, mojo::String, mojo::String)>&
-          callback) override {
+      const String& message,
+      const mojo::Callback<void(String, String, String)>& callback) override {
     callback.Run(app_url_, connection_url_, message);
   }
 
   mojo::StrongBinding<Pingable> binding_;
   std::string app_url_;
   std::string connection_url_;
 };
 
 class PingableApp : public mojo::ApplicationDelegate,
                     public mojo::InterfaceFactory<Pingable> {
@@ skipping 19 matching lines @@
     new PingableImpl(request.Pass(), app_url_, connection->GetConnectionURL());
   }
 
   std::string app_url_;
 };
 
 MojoResult MojoMain(MojoHandle application_request) {
   mojo::ApplicationRunner runner(new PingableApp);
   return runner.Run(application_request);
 }