Reduce timeout for drivefs

As now we have keepalives being sent from drivefs we don't need such a
long timeout to detect stuck service.

BUG=chromium:889732

Change-Id: I828c1e59fb889aba223f45d327cf68c4e5eaf37f
Reviewed-on: https://chromium-review.googlesource.com/c/1309373Reviewed-by: Sam McNally <sammc@chromium.org>
Commit-Queue: Sergei Datsenko <dats@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605233}

chromeos/components/drivefs/drivefs_host.cc

@@ -28,7 +28,7 @@ namespace {
 constexpr char kMountScheme[] = "drivefs://";
 constexpr char kDataPath[] = "GCache/v2";
 constexpr char kIdentityConsumerId[] = "drivefs";
-constexpr base::TimeDelta kMountTimeout = base::TimeDelta::FromMinutes(1);
+constexpr base::TimeDelta kMountTimeout = base::TimeDelta::FromSeconds(20);
 
 class MojoConnectionDelegateImpl : public DriveFsHost::MojoConnectionDelegate {
  public: