Eliminate mojo::Shell client lib class

mojo/shell/public/cpp/lib/message_loop_ref.cc

+// Copyright 2016 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/shell/public/cpp/message_loop_ref.h"
+
+#include "base/bind.h"
+#include "base/message_loop/message_loop.h"
+
+namespace mojo {
+
+class MessageLoopRefImpl : public MessageLoopRef {
+ public:
+  MessageLoopRefImpl(
+      MessageLoopRefFactory* factory,
+      scoped_refptr<base::SingleThreadTaskRunner> app_task_runner)
+      : factory_(factory),
+        app_task_runner_(app_task_runner) {}
+  ~MessageLoopRefImpl() override {
+#ifndef NDEBUG
+    // Ensure that this object is used on only one thread at a time, or else
+    // there could be races where the object is being reset on one thread and
+    // cloned on another.
+    if (clone_task_runner_)
+      DCHECK(clone_task_runner_->BelongsToCurrentThread());
+#endif
+
+    if (app_task_runner_->BelongsToCurrentThread()) {
+      factory_->Release();
+    } else {
+      app_task_runner_->PostTask(
+          FROM_HERE,
+          base::Bind(&MessageLoopRefFactory::Release,
+                     base::Unretained(factory_)));
+    }
+  }
+
+ private:
+  // MessageLoopRef:
+  scoped_ptr<MessageLoopRef> Clone() override {
+    if (app_task_runner_->BelongsToCurrentThread()) {
+      factory_->AddRef();
+    } else {
+      app_task_runner_->PostTask(
+          FROM_HERE,
+          base::Bind(&MessageLoopRefFactory::AddRef,
+                     base::Unretained(factory_)));
+    }
+
+#ifndef NDEBUG
+    // Ensure that this object is used on only one thread at a time, or else
+    // there could be races where the object is being reset on one thread and
+    // cloned on another.
+    if (clone_task_runner_) {
+      DCHECK(clone_task_runner_->BelongsToCurrentThread());
+    } else {
+      clone_task_runner_ = base::MessageLoop::current()->task_runner();
+    }
+#endif
+
+    return make_scoped_ptr(new MessageLoopRefImpl(factory_, app_task_runner_));
+  }
+
+  MessageLoopRefFactory* factory_;
+  scoped_refptr<base::SingleThreadTaskRunner> app_task_runner_;
+
+#ifndef NDEBUG
+  scoped_refptr<base::SingleThreadTaskRunner> clone_task_runner_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(MessageLoopRefImpl);
+};
+
+MessageLoopRefFactory::MessageLoopRefFactory() {}
+MessageLoopRefFactory::~MessageLoopRefFactory() {}
+
+scoped_ptr<MessageLoopRef> MessageLoopRefFactory::CreateRef() {
+  AddRef();
+  return make_scoped_ptr(new MessageLoopRefImpl(
+      this, base::MessageLoop::current()->task_runner()));
+}
+
+void MessageLoopRefFactory::AddRef() {
+  ++ref_count_;
+}
+
+void MessageLoopRefFactory::Release() {
+  if (!--ref_count_) {
+    if (!quit_closure_.is_null())
+      quit_closure_.Run();
+    if (base::MessageLoop::current() &&
+        base::MessageLoop::current()->is_running()) {
+      base::MessageLoop::current()->QuitWhenIdle();
+    }
+  }
+}
+
+}  // namespace mojo