toolchain: Update to Rust 1.31.0

We updated the production toolchain from 1.30 to 1.31 in CL:1366446.
This CL does the same upgrade for the local developer toolchain and
Kokoro.

The relevant changes are in rust-toolchain and kokoro/Dockerfile.
The rest are from rustfmt.

TEST=cargo fmt --all -- --check
TEST=as described in kokoro/README.md

Change-Id: I3b4913f3e237baa36c664b4953be360c09efffd4
Reviewed-on: https://chromium-review.googlesource.com/1374376
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: David Tolnay <dtolnay@chromium.org>
Reviewed-by: Zach Reizner <zachr@chromium.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/devices/src/virtio/vhost/worker.rs b/devices/src/virtio/vhost/worker.rs
index abd063b..e9ee2fb 100644
--- a/devices/src/virtio/vhost/worker.rs
+++ b/devices/src/virtio/vhost/worker.rs
@@ -97,7 +97,8 @@ impl<T: Vhost> Worker<T> {
                     queue.used_ring,
                     queue.avail_ring,
                     None,
-                ).map_err(Error::VhostSetVringAddr)?;
+                )
+                .map_err(Error::VhostSetVringAddr)?;
             self.vhost_handle
                 .set_vring_base(queue_index, 0)
                 .map_err(Error::VhostSetVringBase)?;
@@ -123,7 +124,8 @@ impl<T: Vhost> Worker<T> {
             .and_then(|pc| {
                 pc.add(&self.interrupt_resample_evt, Token::InterruptResample)
                     .and(Ok(pc))
-            }).and_then(|pc| pc.add(&kill_evt, Token::Kill).and(Ok(pc)))
+            })
+            .and_then(|pc| pc.add(&kill_evt, Token::Kill).and(Ok(pc)))
             .map_err(Error::CreatePollContext)?;
 
         'poll: loop {