Introduce background Download process to android

content/browser/android/download_process_host.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 "content/browser/android/download_process_host.h"
+
+#include <string>
+
+#include "base/command_line.h"
+#include "base/strings/utf_string_conversions.h"
+#include "content/public/common/child_process_host.h"
+#include "content/public/common/content_switches.h"
+#include "content/public/common/process_type.h"
+#include "content/public/common/sandbox_type.h"
+#include "content/public/common/sandboxed_process_launcher_delegate.h"
+#include "ipc/ipc_switches.h"
+
+namespace content {
+
+// Delegate to launch the download child process.
+class DownloadSandboxedProcessLauncherDelegate
+    : public content::SandboxedProcessLauncherDelegate {
+ public:
+  DownloadSandboxedProcessLauncherDelegate(content::ChildProcessHost* host)
+      : ipc_fd_(host->TakeClientFileDescriptor()) {}
+
+  ~DownloadSandboxedProcessLauncherDelegate() override {}
+
+  base::ScopedFD TakeIpcFd() override { return std::move(ipc_fd_); }
+
+ private:
+  base::ScopedFD ipc_fd_;
+};
+
+DownloadProcessHost::DownloadProcessHost() : started_(false) {}
+
+DownloadProcessHost::~DownloadProcessHost() {}
+
+bool DownloadProcessHost::StartProcess() {
+  if (started_)
+    return true;
+  started_ = true;
+
+  process_.reset(content::BrowserChildProcessHost::Create(
+      content::PROCESS_TYPE_DOWNLOAD, this));
+  process_->SetName(base::UTF8ToUTF16(switches::kDownloadProcess));
+
+  std::string channel_id = process_->GetHost()->CreateChannel();
+  if (channel_id.empty())
+    return false;
+
+  const base::CommandLine& browser_command_line =
+      *base::CommandLine::ForCurrentProcess();
+
+  base::FilePath exe_path = content::ChildProcessHost::GetChildPath(
+      content::ChildProcessHost::CHILD_NORMAL);
+  if (exe_path.empty()) {
+    NOTREACHED() << "Unable to get download process binary name.";
+    return false;
+  }
+
+  base::CommandLine* cmd_line = new base::CommandLine(exe_path);
+  cmd_line->AppendSwitchASCII(switches::kProcessType,
+                              switches::kDownloadProcess);
+  cmd_line->AppendSwitchASCII(switches::kProcessChannelID, channel_id);
+  cmd_line->AppendSwitch(switches::kNoSandbox);
+
+  process_->Launch(
+      new DownloadSandboxedProcessLauncherDelegate(process_->GetHost()),
+      cmd_line, false);
+
+  return true;
+}
+
+bool DownloadProcessHost::OnMessageReceived(const IPC::Message& message) {
+  NOTIMPLEMENTED();
+  return true;
+}
+
+void DownloadProcessHost::OnProcessLaunchFailed() {
+  NOTIMPLEMENTED();
+}
+
+void DownloadProcessHost::OnProcessCrashed(int exit_code) {
+  NOTIMPLEMENTED();
+}
+
+void DownloadProcessHost::OnProcessLaunched() {
+  NOTIMPLEMENTED();
+}
+
+}  // namespace content