Add the UtilityProcessMojoClient class and convert SafeJsonParser

content/public/browser/utility_process_mojo_client.h

+// 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.
+
+#ifndef CONTENT_PUBLIC_BROWSER_UTILITY_PROCESS_MOJO_CLIENT_H_
+#define CONTENT_PUBLIC_BROWSER_UTILITY_PROCESS_MOJO_CLIENT_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/strings/string16.h"
+#include "base/threading/thread_checker.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/utility_process_host.h"
+#include "content/public/browser/utility_process_host_client.h"
+#include "content/public/common/service_registry.h"
+#include "mojo/public/cpp/bindings/interface_ptr.h"
+
+namespace content {
+
+// Implements a client to a Mojo service running on a utility process. Takes
+// care of starting the utility process and connecting to the remote Mojo
+// service. The utility process is terminated in the destructor.
+// Note: This class is not thread-safe. It is bound to the
+// SingleThreadTaskRunner it is created on.
+template <class MojoInterface>
+class UtilityProcessMojoClient {
+ public:
+  UtilityProcessMojoClient(const base::string16& process_name,
+                           const base::Closure& on_error_callback)
+      : on_error_callback_(on_error_callback) {
+    DCHECK(!on_error_callback_.is_null());
+    helper_.reset(new Helper(process_name));
+  }
+
+  ~UtilityProcessMojoClient() {
+    BrowserThread::DeleteSoon(BrowserThread::IO, FROM_HERE, helper_.release());
+  }
+
+  // Disables the sandbox in the utility process.
+  void set_disable_sandbox() {
+    DCHECK(!start_called_);
+    helper_->set_disable_sandbox();
+  }
+
+  // Starts the utility process and connect to the remote Mojo service.
+  void Start() {
+    DCHECK(thread_checker_.CalledOnValidThread());
+    DCHECK(!start_called_);
+
+    start_called_ = true;
+
+    mojo::InterfaceRequest<MojoInterface> req = mojo::GetProxy(&service_);
+
+    service_.set_connection_error_handler(on_error_callback_);
+
+    helper_->Start(MojoInterface::Name_, req.PassMessagePipe());
+  }
+
+  // Returns the Mojo service used to make calls to the utility process.
+  MojoInterface* service() WARN_UNUSED_RESULT {
+    DCHECK(thread_checker_.CalledOnValidThread());
+    DCHECK(start_called_);
+
+    return service_.get();
+  }
+
+ private:
+  // Helper class that takes care of managing the lifetime of the utility
+  // process on the IO thread.
+  class Helper {
+   public:
+    explicit Helper(const base::string16& process_name)
+        : process_name_(process_name) {}
+
+    ~Helper() {
+      DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+      // |utility_host_| manages its own lifetime but this forces the process to
+      // terminate if it's still alive.
+      delete utility_host_.get();
+    }
+
+    // Starts the utility process on the IO thread.
+    void Start(const std::string& mojo_interface_name,
+               mojo::ScopedMessagePipeHandle interface_pipe) {
+      BrowserThread::PostTask(
+          BrowserThread::IO, FROM_HERE,
+          base::Bind(&Helper::StartOnIOThread, base::Unretained(this),
+                     mojo_interface_name, base::Passed(&interface_pipe)));
+    }
+
+    void set_disable_sandbox() { disable_sandbox_ = true; }
+
+   private:
+    // Starts the utility process and connects to the remote Mojo service.
+    void StartOnIOThread(const std::string& mojo_interface_name,
+                         mojo::ScopedMessagePipeHandle interface_pipe) {
+      DCHECK_CURRENTLY_ON(BrowserThread::IO);
+      utility_host_ = UtilityProcessHost::Create(nullptr, nullptr)->AsWeakPtr();
+      utility_host_->SetName(process_name_);
+      if (disable_sandbox_)
+        utility_host_->DisableSandbox();
+
+      utility_host_->Start();
+
+      ServiceRegistry* service_registry = utility_host_->GetServiceRegistry();
+      service_registry->ConnectToRemoteService(mojo_interface_name,
+                                               std::move(interface_pipe));
+    }
+
+    // Properties of the utility process.
+    base::string16 process_name_;
+    bool disable_sandbox_ = false;
+
+    // Must only be accessed on the IO thread.
+    base::WeakPtr<UtilityProcessHost> utility_host_;
+
+    DISALLOW_COPY_AND_ASSIGN(Helper);
+  };
+
+  std::unique_ptr<Helper> helper_;
+
+  // Called when a connection error happens or if the process didn't start.
+  base::Closure on_error_callback_;
+
+  mojo::InterfacePtr<MojoInterface> service_;
+
+  // Enforce calling Start() before getting the service.
+  bool start_called_ = false;
+
+  // Checks that this class is always accessed from the same thread.
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(UtilityProcessMojoClient);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_UTILITY_PROCESS_MOJO_CLIENT_H_