Embed a mojo ApplicationManager in content/browser

content/public/common/static_mojo_application_loader.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 "content/public/common/static_mojo_application_loader.h"
+
+#include "base/bind.h"
+#include "base/lazy_instance.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/message_loop/message_loop.h"
+#include "base/task_runner.h"
+#include "base/thread_task_runner_handle.h"
+#include "base/threading/thread.h"
+#include "base/threading/thread_local.h"
+#include "mojo/application/public/cpp/application_delegate.h"
+#include "mojo/application/public/cpp/application_impl.h"
+#include "mojo/application/public/interfaces/application.mojom.h"
+#include "mojo/common/message_pump_mojo.h"
+#include "third_party/mojo/src/mojo/public/cpp/bindings/interface_request.h"
+
+namespace content {
+
+namespace {
+
+class Runner;
+
+// Tracks each application's Runner on its main thread.
+base::LazyInstance<base::ThreadLocalPointer<Runner>> g_runner;
+
+void TerminateCurrentApp();
+
+// Container for a single instance of the loaded application. This lives and
+// dies on the app instance's own thread and kills itself either when the thread
+// message loop is destroyed or the app terminates itself.
+class Runner : public base::MessageLoop::DestructionObserver {
+ public:
+  Runner(mojo::InterfaceRequest<mojo::Application> request,
+         scoped_refptr<base::TaskRunner> exit_task_runner,
+         const base::Closure& exit_callback,
+         scoped_ptr<mojo::ApplicationDelegate> delegate)
+      : exit_task_runner_(exit_task_runner),
+        exit_callback_(exit_callback),
+        delegate_(delegate.Pass()) {
+    DCHECK(base::MessageLoop::current());
+    DCHECK(!g_runner.Get().Get());
+    g_runner.Get().Set(this);
+    base::MessageLoop::current()->AddDestructionObserver(this);
+    application_.reset(
+        new mojo::ApplicationImpl(delegate_.get(), request.Pass(),
+                                  base::Bind(&TerminateCurrentApp)));
+  }
+
+ private:
+  friend void TerminateCurrentApp();
+
+  ~Runner() override {
+    g_runner.Get().Set(nullptr);
+    base::MessageLoop::current()->RemoveDestructionObserver(this);
+    exit_task_runner_->PostTask(FROM_HERE, exit_callback_);
+  }
+
+  // base::MessageLoop::DestructionObserver:
+  void WillDestroyCurrentMessageLoop() override {
+    DCHECK(base::MessageLoop::current());
+    delete this;
+  }
+
+  scoped_refptr<base::TaskRunner> exit_task_runner_;
+  base::Closure exit_callback_;
+  scoped_ptr<mojo::ApplicationDelegate> delegate_;
+  scoped_ptr<mojo::ApplicationImpl> application_;
+
+  DISALLOW_COPY_AND_ASSIGN(Runner);
+};
+
+void RunAppOnOwnThread(
+    mojo::InterfaceRequest<mojo::Application> request,
+    scoped_refptr<base::TaskRunner> exit_task_runner,
+    const base::Closure& exit_callback,
+    const StaticMojoApplicationLoader::ApplicationFactory& factory) {
+  // This object either destroys itself when the current MessageLoop is
+  // destroyed, or it is destroyed by TerminateCurrentApp (see below).
+  new Runner(request.Pass(), exit_task_runner, exit_callback, factory.Run());
+}
+
+// This is run on an app's own thread when its ApplicationImpl::Terminate()
+// method is called.
+void TerminateCurrentApp() {
+  Runner* runner = g_runner.Get().Get();
+  DCHECK(runner);
+  delete runner;
+}
+
+}  // namespace
+
+StaticMojoApplicationLoader::StaticMojoApplicationLoader(
+    const ApplicationFactory& factory)
+    : StaticMojoApplicationLoader(factory, base::Closure()) {
+}
+
+StaticMojoApplicationLoader::StaticMojoApplicationLoader(
+    const ApplicationFactory& factory,
+    const base::Closure& quit_callback)
+    : factory_(factory),
+      quit_callback_(quit_callback),
+      weak_factory_(this) {
+}
+
+StaticMojoApplicationLoader::~StaticMojoApplicationLoader() {
+}
+
+void StaticMojoApplicationLoader::Load(
+    const GURL& url,
+    mojo::InterfaceRequest<mojo::Application> request) {
+  threads_.insert(threads_.begin(), make_scoped_ptr(new base::Thread(
+      "Mojo Application: " + url.spec())));
+  base::Thread::Options options;
+  options.message_pump_factory =
+      base::Bind(&mojo::common::MessagePumpMojo::Create);
+  threads_.front()->StartWithOptions(options);
+
+  // If the application's thread quits on its own before this loader dies, we
+  // evict the Thread object from |threads_| and destroy it.
+  auto exit_callback = base::Bind(
+      &StaticMojoApplicationLoader::CleanUpAppThread,
+      weak_factory_.GetWeakPtr(), threads_.begin());
+  threads_.front()->task_runner()->PostTask(
+      FROM_HERE,
+      base::Bind(&RunAppOnOwnThread, base::Passed(&request),
+                 base::ThreadTaskRunnerHandle::Get(), exit_callback, factory_));
+}
+
+void StaticMojoApplicationLoader::CleanUpAppThread(
+    typename ThreadList::iterator iter) {
+  threads_.erase(iter);
+  if (!quit_callback_.is_null())
+    quit_callback_.Run();
+}
+
+}  // namespace content