Code:   explicit MountState(DriveFsHost* host)
      : host_(host),
        mojo_connection_delegate_(
            host_->delegate_->CreateMojoConnectionDelegate()),
        pending_token_(base::UnguessableToken::Create()),
        binding_(this) {
    source_path_ = base::StrCat({kMountScheme, pending_token_.ToString()});
    std::string datadir_option = base::StrCat(
        {"datadir=",
          host_->profile_path_.Append(kDataPath)
              .Append(host_->delegate_->GetAccountId().GetAccountIdKey())
              .value()});
    chromeos::disks::DiskMountManager::GetInstance()->MountPath(
        source_path_, "",
        base::StrCat(
            {"drivefs-", host_->delegate_->GetAccountId().GetAccountIdKey()}),
        {datadir_option}, chromeos::MOUNT_TYPE_NETWORK_STORAGE,
        chromeos::MOUNT_ACCESS_MODE_READ_WRITE);
     auto bootstrap =
         mojo::MakeProxy(mojo_connection_delegate_->InitializeMojoConnection());
     mojom::DriveFsDelegatePtr delegate;
    binding_.Bind(mojo::MakeRequest(&delegate));
    bootstrap->Init(
        {base::in_place, host_->delegate_->GetAccountId().GetUserEmail()},
        mojo::MakeRequest(&drivefs_), std::move(delegate));

    PendingConnectionManager::Get().ExpectOpenIpcChannel(
         pending_token_,
         base::BindOnce(&DriveFsHost::MountState::AcceptMojoConnection,
                        base::Unretained(this)));
   }

Vulnerability Type: DoS 
CWE ID: 
Summary: Multiple unspecified vulnerabilities in Google Chrome before 47.0.2526.80 allow attackers to cause a denial of service or possibly have other impact via unknown vectors.
Commit Message: Add a fake DriveFS launcher client.

Using DriveFS requires building and deploying ChromeOS. Add a client for
the fake DriveFS launcher to allow the use of a real DriveFS from a
ChromeOS chroot to be used with a target_os="chromeos" build of chrome.
This connects to the fake DriveFS launcher using mojo over a unix domain
socket named by a command-line flag, using the launcher to create
DriveFS instances.

Bug: 848126
Change-Id: I22dcca154d41bda196dd7c1782bb503f6bcba5b1
Reviewed-on: https://chromium-review.googlesource.com/1098434
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Sam McNally <sammc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567513}