diff --git a/dom/webauthn/u2f-hid-rs/Cargo.toml b/dom/webauthn/u2f-hid-rs/Cargo.toml
index 547dea8ab380..5d52318e7a2b 100644
--- a/dom/webauthn/u2f-hid-rs/Cargo.toml
+++ b/dom/webauthn/u2f-hid-rs/Cargo.toml
@@ -18,6 +18,7 @@ log = "0.3"
 env_logger = "0.4.1"
 libc = "^0.2"
 boxfnonce = "0.0.3"
+runloop = "0.1.0"
 
 [dev-dependencies]
 rust-crypto = "^0.2"
diff --git a/dom/webauthn/u2f-hid-rs/src/lib.rs b/dom/webauthn/u2f-hid-rs/src/lib.rs
index 2ff068963551..a22667b007db 100644
--- a/dom/webauthn/u2f-hid-rs/src/lib.rs
+++ b/dom/webauthn/u2f-hid-rs/src/lib.rs
@@ -32,9 +32,9 @@ extern crate log;
 extern crate rand;
 extern crate libc;
 extern crate boxfnonce;
+extern crate runloop;
 
 mod consts;
-mod runloop;
 mod u2ftypes;
 mod u2fprotocol;
 
diff --git a/dom/webauthn/u2f-hid-rs/src/linux/mod.rs b/dom/webauthn/u2f-hid-rs/src/linux/mod.rs
index bf633eac0e87..464d85e3559e 100644
--- a/dom/webauthn/u2f-hid-rs/src/linux/mod.rs
+++ b/dom/webauthn/u2f-hid-rs/src/linux/mod.rs
@@ -40,7 +40,7 @@ impl PlatformManager {
 
         let cbc = callback.clone();
 
-        let thread = RunLoop::new(
+        let thread = RunLoop::new_with_timeout(
             move |alive| {
                 let mut devices = DeviceMap::new();
                 let monitor = try_or!(Monitor::new(), |e| { callback.call(Err(e)); });
@@ -87,7 +87,7 @@ impl PlatformManager {
 
         let cbc = callback.clone();
 
-        let thread = RunLoop::new(
+        let thread = RunLoop::new_with_timeout(
             move |alive| {
                 let mut devices = DeviceMap::new();
                 let monitor = try_or!(Monitor::new(), |e| { callback.call(Err(e)); });
diff --git a/dom/webauthn/u2f-hid-rs/src/linux/monitor.rs b/dom/webauthn/u2f-hid-rs/src/linux/monitor.rs
index 2c7511cd3065..7d66cf1dc829 100644
--- a/dom/webauthn/u2f-hid-rs/src/linux/monitor.rs
+++ b/dom/webauthn/u2f-hid-rs/src/linux/monitor.rs
@@ -100,9 +100,7 @@ impl Monitor {
                 }
 
                 Ok(())
-            },
-            0, /* no timeout */
-        )?;
+            })?;
 
         Ok(Self { rx, thread })
     }
diff --git a/dom/webauthn/u2f-hid-rs/src/macos/mod.rs b/dom/webauthn/u2f-hid-rs/src/macos/mod.rs
index 530e84dda07e..f13e48f66700 100644
--- a/dom/webauthn/u2f-hid-rs/src/macos/mod.rs
+++ b/dom/webauthn/u2f-hid-rs/src/macos/mod.rs
@@ -45,7 +45,7 @@ impl PlatformManager {
 
         let cbc = callback.clone();
 
-        let thread = RunLoop::new(
+        let thread = RunLoop::new_with_timeout(
             move |alive| {
                 let mut devices = DeviceMap::new();
                 let monitor = try_or!(Monitor::new(), |e| { callback.call(Err(e)); });
@@ -98,7 +98,7 @@ impl PlatformManager {
 
         let cbc = callback.clone();
 
-        let thread = RunLoop::new(
+        let thread = RunLoop::new_with_timeout(
             move |alive| {
                 let mut devices = DeviceMap::new();
                 let monitor = try_or!(Monitor::new(), |e| { callback.call(Err(e)); });
diff --git a/dom/webauthn/u2f-hid-rs/src/macos/monitor.rs b/dom/webauthn/u2f-hid-rs/src/macos/monitor.rs
index 5d25c91ddfff..147b76b067a0 100644
--- a/dom/webauthn/u2f-hid-rs/src/macos/monitor.rs
+++ b/dom/webauthn/u2f-hid-rs/src/macos/monitor.rs
@@ -31,53 +31,50 @@ impl Monitor {
     pub fn new() -> io::Result<Self> {
         let (tx, rx) = channel();
 
-        let thread = RunLoop::new(
-            move |alive| -> io::Result<()> {
-                let tx_box = Box::new(tx);
-                let tx_ptr = Box::into_raw(tx_box) as *mut libc::c_void;
+        let thread = RunLoop::new(move |alive| -> io::Result<()> {
+            let tx_box = Box::new(tx);
+            let tx_ptr = Box::into_raw(tx_box) as *mut libc::c_void;
 
-                // This will keep `tx` alive only for the scope.
-                let _tx = unsafe { Box::from_raw(tx_ptr as *mut Sender<Event>) };
+            // This will keep `tx` alive only for the scope.
+            let _tx = unsafe { Box::from_raw(tx_ptr as *mut Sender<Event>) };
 
-                // Create and initialize a scoped HID manager.
-                let manager = IOHIDManager::new()?;
+            // Create and initialize a scoped HID manager.
+            let manager = IOHIDManager::new()?;
 
-                // Match only U2F devices.
-                let dict = IOHIDDeviceMatcher::new();
-                unsafe { IOHIDManagerSetDeviceMatching(manager.get(), dict.get()) };
+            // Match only U2F devices.
+            let dict = IOHIDDeviceMatcher::new();
+            unsafe { IOHIDManagerSetDeviceMatching(manager.get(), dict.get()) };
 
-                // Register callbacks.
-                unsafe {
-                    IOHIDManagerRegisterDeviceMatchingCallback(
-                        manager.get(),
-                        Monitor::device_add_cb,
-                        tx_ptr,
-                    );
-                    IOHIDManagerRegisterDeviceRemovalCallback(
-                        manager.get(),
-                        Monitor::device_remove_cb,
-                        tx_ptr,
-                    );
+            // Register callbacks.
+            unsafe {
+                IOHIDManagerRegisterDeviceMatchingCallback(
+                    manager.get(),
+                    Monitor::device_add_cb,
+                    tx_ptr,
+                );
+                IOHIDManagerRegisterDeviceRemovalCallback(
+                    manager.get(),
+                    Monitor::device_remove_cb,
+                    tx_ptr,
+                );
+            }
+
+            // Run the Event Loop. CFRunLoopRunInMode() will dispatch HID
+            // input reports into the various callbacks
+            while alive() {
+                trace!("OSX Runloop running, handle={:?}", thread::current());
+
+                if unsafe { CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.1, 0) } ==
+                    kCFRunLoopRunStopped
+                {
+                    debug!("OSX Runloop device stopped.");
+                    break;
                 }
+            }
+            debug!("OSX Runloop completed, handle={:?}", thread::current());
 
-                // Run the Event Loop. CFRunLoopRunInMode() will dispatch HID
-                // input reports into the various callbacks
-                while alive() {
-                    trace!("OSX Runloop running, handle={:?}", thread::current());
-
-                    if unsafe { CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.1, 0) } ==
-                        kCFRunLoopRunStopped
-                    {
-                        debug!("OSX Runloop device stopped.");
-                        break;
-                    }
-                }
-                debug!("OSX Runloop completed, handle={:?}", thread::current());
-
-                Ok(())
-            },
-            0, /* no timeout */
-        )?;
+            Ok(())
+        })?;
 
         Ok(Self { rx, thread })
     }
diff --git a/dom/webauthn/u2f-hid-rs/src/manager.rs b/dom/webauthn/u2f-hid-rs/src/manager.rs
index 5b2688181934..a6320a824711 100644
--- a/dom/webauthn/u2f-hid-rs/src/manager.rs
+++ b/dom/webauthn/u2f-hid-rs/src/manager.rs
@@ -38,48 +38,45 @@ impl U2FManager {
         let (tx, rx) = channel();
 
         // Start a new work queue thread.
-        let queue = try!(RunLoop::new(
-            move |alive| {
-                let mut pm = PlatformManager::new();
+        let queue = RunLoop::new(move |alive| {
+            let mut pm = PlatformManager::new();
 
-                while alive() {
-                    match rx.recv_timeout(Duration::from_millis(50)) {
-                        Ok(QueueAction::Register {
-                               timeout,
-                               challenge,
-                               application,
-                               callback,
-                           }) => {
-                            // This must not block, otherwise we can't cancel.
-                            pm.register(timeout, challenge, application, callback);
-                        }
-                        Ok(QueueAction::Sign {
-                               timeout,
-                               challenge,
-                               application,
-                               key_handles,
-                               callback,
-                           }) => {
-                            // This must not block, otherwise we can't cancel.
-                            pm.sign(timeout, challenge, application, key_handles, callback);
-                        }
-                        Ok(QueueAction::Cancel) => {
-                            // Cancelling must block so that we don't start a new
-                            // polling thread before the old one has shut down.
-                            pm.cancel();
-                        }
-                        Err(RecvTimeoutError::Disconnected) => {
-                            break;
-                        }
-                        _ => { /* continue */ }
+            while alive() {
+                match rx.recv_timeout(Duration::from_millis(50)) {
+                    Ok(QueueAction::Register {
+                           timeout,
+                           challenge,
+                           application,
+                           callback,
+                       }) => {
+                        // This must not block, otherwise we can't cancel.
+                        pm.register(timeout, challenge, application, callback);
                     }
+                    Ok(QueueAction::Sign {
+                           timeout,
+                           challenge,
+                           application,
+                           key_handles,
+                           callback,
+                       }) => {
+                        // This must not block, otherwise we can't cancel.
+                        pm.sign(timeout, challenge, application, key_handles, callback);
+                    }
+                    Ok(QueueAction::Cancel) => {
+                        // Cancelling must block so that we don't start a new
+                        // polling thread before the old one has shut down.
+                        pm.cancel();
+                    }
+                    Err(RecvTimeoutError::Disconnected) => {
+                        break;
+                    }
+                    _ => { /* continue */ }
                 }
+            }
 
-                // Cancel any ongoing activity.
-                pm.cancel();
-            },
-            0, /* no timeout */
-        ));
+            // Cancel any ongoing activity.
+            pm.cancel();
+        })?;
 
         Ok(Self {
             queue: queue,
diff --git a/dom/webauthn/u2f-hid-rs/src/windows/mod.rs b/dom/webauthn/u2f-hid-rs/src/windows/mod.rs
index 728bf27bcb9e..ee4189b765d7 100644
--- a/dom/webauthn/u2f-hid-rs/src/windows/mod.rs
+++ b/dom/webauthn/u2f-hid-rs/src/windows/mod.rs
@@ -40,7 +40,7 @@ impl PlatformManager {
 
         let cbc = callback.clone();
 
-        let thread = RunLoop::new(
+        let thread = RunLoop::new_with_timeout(
             move |alive| {
                 let mut devices = DeviceMap::new();
                 let monitor = try_or!(Monitor::new(), |e| { callback.call(Err(e)); });
@@ -86,7 +86,7 @@ impl PlatformManager {
 
         let cbc = callback.clone();
 
-        let thread = RunLoop::new(
+        let thread = RunLoop::new_with_timeout(
             move |alive| {
                 let mut devices = DeviceMap::new();
                 let monitor = try_or!(Monitor::new(), |e| { callback.call(Err(e)); });
diff --git a/dom/webauthn/u2f-hid-rs/src/windows/monitor.rs b/dom/webauthn/u2f-hid-rs/src/windows/monitor.rs
index 38a4879df388..6c063a10cb8c 100644
--- a/dom/webauthn/u2f-hid-rs/src/windows/monitor.rs
+++ b/dom/webauthn/u2f-hid-rs/src/windows/monitor.rs
@@ -63,9 +63,7 @@ impl Monitor {
                 }
 
                 Ok(())
-            },
-            0, /* no timeout */
-        )?;
+            })?;
 
         Ok(Self {
             rx: rx,
diff --git a/third_party/rust/runloop/.cargo-checksum.json b/third_party/rust/runloop/.cargo-checksum.json
new file mode 100644
index 000000000000..417387fe1aa6
--- /dev/null
+++ b/third_party/rust/runloop/.cargo-checksum.json
@@ -0,0 +1 @@
+{"files":{".cargo-ok":"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",".travis.yml":"0b87ec61b2b5ea3d71356aa08965587185b70ea2e00d68dab69c7db893a4499a","Cargo.toml":"6148ea66fe5c0f49d36f01cc88b7aaf90a058ffb406402f0c9e8d790b32a509d","LICENSE":"b946744aeda89b467929585fe8eeb5461847695220c1b168fb375d8abd4ea3d0","README.md":"466aa6f249e465158175bd05567c1c9b996c3a57e22666ef78273e2a2f5a3f02","rustfmt.toml":"de4e1daab481c1572805aed3e51e72c5dc1b3e5af757bc675e1717b251c6e922","src/lib.rs":"e904c1c9d0fbc6dcf9749346f9ee612747e9755b33f60d57689249594d6b0750"},"package":"5d79b4b604167921892e84afbbaad9d5ad74e091bf6c511d9dbfb0593f09fabd"}
\ No newline at end of file
diff --git a/third_party/rust/runloop/.cargo-ok b/third_party/rust/runloop/.cargo-ok
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/third_party/rust/runloop/.travis.yml b/third_party/rust/runloop/.travis.yml
new file mode 100644
index 000000000000..22c4708a699a
--- /dev/null
+++ b/third_party/rust/runloop/.travis.yml
@@ -0,0 +1,16 @@
+sudo: false
+language: rust
+cache: cargo
+rust:
+  - stable
+  - beta
+  - nightly
+
+before_install:
+  - cargo install rustfmt || true
+
+script:
+- |
+  cargo fmt -- --write-mode=diff &&
+  cargo build &&
+  cargo test
diff --git a/third_party/rust/runloop/Cargo.toml b/third_party/rust/runloop/Cargo.toml
new file mode 100644
index 000000000000..3746a73a5dfa
--- /dev/null
+++ b/third_party/rust/runloop/Cargo.toml
@@ -0,0 +1,22 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g. crates.io) dependencies
+#
+# If you believe there's an error in this file please file an
+# issue against the rust-lang/cargo repository. If you're
+# editing this file be aware that the upstream Cargo.toml
+# will likely look very different (and much more reasonable)
+
+[package]
+name = "runloop"
+version = "0.1.0"
+authors = ["Tim Taubert <tim@timtaubert.de>"]
+description = "Cancelable non-blocking polling threads (with optional timeouts)."
+homepage = "https://github.com/ttaubert/rust-runloop/"
+readme = "README.md"
+keywords = ["runloop", "threads"]
+license = "MPL-2.0"
+repository = "https://github.com/ttaubert/rust-runloop/"
diff --git a/third_party/rust/runloop/LICENSE b/third_party/rust/runloop/LICENSE
new file mode 100644
index 000000000000..398385c9fb9b
--- /dev/null
+++ b/third_party/rust/runloop/LICENSE
@@ -0,0 +1,374 @@
+ Mozilla Public License Version 2.0
+==================================
+
+1. Definitions
+--------------
+
+1.1. "Contributor"
+means each individual or legal entity that creates, contributes to
+the creation of, or owns Covered Software.
+
+1.2. "Contributor Version"
+means the combination of the Contributions of others (if any) used
+by a Contributor and that particular Contributor's Contribution.
+
+1.3. "Contribution"
+means Covered Software of a particular Contributor.
+
+1.4. "Covered Software"
+means Source Code Form to which the initial Contributor has attached
+the notice in Exhibit A, the Executable Form of such Source Code
+Form, and Modifications of such Source Code Form, in each case
+including portions thereof.
+
+1.5. "Incompatible With Secondary Licenses"
+means
+
+(a) that the initial Contributor has attached the notice described
+in Exhibit B to the Covered Software; or
+
+(b) that the Covered Software was made available under the terms of
+version 1.1 or earlier of the License, but not also under the
+terms of a Secondary License.
+
+1.6. "Executable Form"
+means any form of the work other than Source Code Form.
+
+1.7. "Larger Work"
+means a work that combines Covered Software with other material, in
+a separate file or files, that is not Covered Software.
+
+1.8. "License"
+means this document.
+
+1.9. "Licensable"
+means having the right to grant, to the maximum extent possible,
+whether at the time of the initial grant or subsequently, any and
+all of the rights conveyed by this License.
+
+1.10. "Modifications"
+means any of the following:
+
+(a) any file in Source Code Form that results from an addition to,
+deletion from, or modification of the contents of Covered
+Software; or
+
+(b) any new file in Source Code Form that contains any Covered
+Software.
+
+1.11. "Patent Claims" of a Contributor
+means any patent claim(s), including without limitation, method,
+process, and apparatus claims, in any patent Licensable by such
+Contributor that would be infringed, but for the grant of the
+License, by the making, using, selling, offering for sale, having
+made, import, or transfer of either its Contributions or its
+Contributor Version.
+
+1.12. "Secondary License"
+means either the GNU General Public License, Version 2.0, the GNU
+Lesser General Public License, Version 2.1, the GNU Affero General
+Public License, Version 3.0, or any later versions of those
+licenses.
+
+1.13. "Source Code Form"
+means the form of the work preferred for making modifications.
+
+1.14. "You" (or "Your")
+means an individual or a legal entity exercising rights under this
+License. For legal entities, "You" includes any entity that
+controls, is controlled by, or is under common control with You. For
+purposes of this definition, "control" means (a) the power, direct
+or indirect, to cause the direction or management of such entity,
+whether by contract or otherwise, or (b) ownership of more than
+fifty percent (50%) of the outstanding shares or beneficial
+ownership of such entity.
+
+2. License Grants and Conditions
+--------------------------------
+
+2.1. Grants
+
+Each Contributor hereby grants You a world-wide, royalty-free,
+non-exclusive license:
+
+(a) under intellectual property rights (other than patent or trademark)
+Licensable by such Contributor to use, reproduce, make available,
+modify, display, perform, distribute, and otherwise exploit its
+Contributions, either on an unmodified basis, with Modifications, or
+as part of a Larger Work; and
+
+(b) under Patent Claims of such Contributor to make, use, sell, offer
+for sale, have made, import, and otherwise transfer either its
+Contributions or its Contributor Version.
+
+2.2. Effective Date
+
+The licenses granted in Section 2.1 with respect to any Contribution
+become effective for each Contribution on the date the Contributor first
+distributes such Contribution.
+
+2.3. Limitations on Grant Scope
+
+The licenses granted in this Section 2 are the only rights granted under
+this License. No additional rights or licenses will be implied from the
+distribution or licensing of Covered Software under this License.
+Notwithstanding Section 2.1(b) above, no patent license is granted by a
+Contributor:
+
+(a) for any code that a Contributor has removed from Covered Software;
+or
+
+(b) for infringements caused by: (i) Your and any other third party's
+modifications of Covered Software, or (ii) the combination of its
+Contributions with other software (except as part of its Contributor
+Version); or
+
+(c) under Patent Claims infringed by Covered Software in the absence of
+its Contributions.
+
+This License does not grant any rights in the trademarks, service marks,
+or logos of any Contributor (except as may be necessary to comply with
+the notice requirements in Section 3.4).
+
+2.4. Subsequent Licenses
+
+No Contributor makes additional grants as a result of Your choice to
+distribute the Covered Software under a subsequent version of this
+License (see Section 10.2) or under the terms of a Secondary License (if
+permitted under the terms of Section 3.3).
+
+2.5. Representation
+
+Each Contributor represents that the Contributor believes its
+Contributions are its original creation(s) or it has sufficient rights
+to grant the rights to its Contributions conveyed by this License.
+
+2.6. Fair Use
+
+This License is not intended to limit any rights You have under
+applicable copyright doctrines of fair use, fair dealing, or other
+equivalents.
+
+2.7. Conditions
+
+Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted
+in Section 2.1.
+
+3. Responsibilities
+-------------------
+
+3.1. Distribution of Source Form
+
+All distribution of Covered Software in Source Code Form, including any
+Modifications that You create or to which You contribute, must be under
+the terms of this License. You must inform recipients that the Source
+Code Form of the Covered Software is governed by the terms of this
+License, and how they can obtain a copy of this License. You may not
+attempt to alter or restrict the recipients' rights in the Source Code
+Form.
+
+3.2. Distribution of Executable Form
+
+If You distribute Covered Software in Executable Form then:
+
+(a) such Covered Software must also be made available in Source Code
+Form, as described in Section 3.1, and You must inform recipients of
+the Executable Form how they can obtain a copy of such Source Code
+Form by reasonable means in a timely manner, at a charge no more
+than the cost of distribution to the recipient; and
+
+(b) You may distribute such Executable Form under the terms of this
+License, or sublicense it under different terms, provided that the
+license for the Executable Form does not attempt to limit or alter
+the recipients' rights in the Source Code Form under this License.
+
+3.3. Distribution of a Larger Work
+
+You may create and distribute a Larger Work under terms of Your choice,
+provided that You also comply with the requirements of this License for
+the Covered Software. If the Larger Work is a combination of Covered
+Software with a work governed by one or more Secondary Licenses, and the
+Covered Software is not Incompatible With Secondary Licenses, this
+License permits You to additionally distribute such Covered Software
+under the terms of such Secondary License(s), so that the recipient of
+the Larger Work may, at their option, further distribute the Covered
+Software under the terms of either this License or such Secondary
+License(s).
+
+3.4. Notices
+
+You may not remove or alter the substance of any license notices
+(including copyright notices, patent notices, disclaimers of warranty,
+or limitations of liability) contained within the Source Code Form of
+the Covered Software, except that You may alter any license notices to
+the extent required to remedy known factual inaccuracies.
+
+3.5. Application of Additional Terms
+
+You may choose to offer, and to charge a fee for, warranty, support,
+indemnity or liability obligations to one or more recipients of Covered
+Software. However, You may do so only on Your own behalf, and not on
+behalf of any Contributor. You must make it absolutely clear that any
+such warranty, support, indemnity, or liability obligation is offered by
+You alone, and You hereby agree to indemnify every Contributor for any
+liability incurred by such Contributor as a result of warranty, support,
+indemnity or liability terms You offer. You may include additional
+disclaimers of warranty and limitations of liability specific to any
+jurisdiction.
+
+4. Inability to Comply Due to Statute or Regulation
+---------------------------------------------------
+
+If it is impossible for You to comply with any of the terms of this
+License with respect to some or all of the Covered Software due to
+statute, judicial order, or regulation then You must: (a) comply with
+the terms of this License to the maximum extent possible; and (b)
+describe the limitations and the code they affect. Such description must
+be placed in a text file included with all distributions of the Covered
+Software under this License. Except to the extent prohibited by statute
+or regulation, such description must be sufficiently detailed for a
+recipient of ordinary skill to be able to understand it.
+
+5. Termination
+--------------
+
+5.1. The rights granted under this License will terminate automatically
+if You fail to comply with any of its terms. However, if You become
+compliant, then the rights granted under this License from a particular
+Contributor are reinstated (a) provisionally, unless and until such
+Contributor explicitly and finally terminates Your grants, and (b) on an
+ongoing basis, if such Contributor fails to notify You of the
+non-compliance by some reasonable means prior to 60 days after You have
+come back into compliance. Moreover, Your grants from a particular
+Contributor are reinstated on an ongoing basis if such Contributor
+notifies You of the non-compliance by some reasonable means, this is the
+first time You have received notice of non-compliance with this License
+from such Contributor, and You become compliant prior to 30 days after
+Your receipt of the notice.
+
+5.2. If You initiate litigation against any entity by asserting a patent
+infringement claim (excluding declaratory judgment actions,
+counter-claims, and cross-claims) alleging that a Contributor Version
+directly or indirectly infringes any patent, then the rights granted to
+You by any and all Contributors for the Covered Software under Section
+2.1 of this License shall terminate.
+
+5.3. In the event of termination under Sections 5.1 or 5.2 above, all
+end user license agreements (excluding distributors and resellers) which
+have been validly granted by You or Your distributors under this License
+prior to termination shall survive termination.
+
+************************************************************************
+* *
+* 6. Disclaimer of Warranty *
+* ------------------------- *
+* *
+* Covered Software is provided under this License on an "as is" *
+* basis, without warranty of any kind, either expressed, implied, or *
+* statutory, including, without limitation, warranties that the *
+* Covered Software is free of defects, merchantable, fit for a *
+* particular purpose or non-infringing. The entire risk as to the *
+* quality and performance of the Covered Software is with You. *
+* Should any Covered Software prove defective in any respect, You *
+* (not any Contributor) assume the cost of any necessary servicing, *
+* repair, or correction. This disclaimer of warranty constitutes an *
+* essential part of this License. No use of any Covered Software is *
+* authorized under this License except under this disclaimer. *
+* *
+************************************************************************
+
+************************************************************************
+* *
+* 7. Limitation of Liability *
+* -------------------------- *
+* *
+* Under no circumstances and under no legal theory, whether tort *
+* (including negligence), contract, or otherwise, shall any *
+* Contributor, or anyone who distributes Covered Software as *
+* permitted above, be liable to You for any direct, indirect, *
+* special, incidental, or consequential damages of any character *
+* including, without limitation, damages for lost profits, loss of *
+* goodwill, work stoppage, computer failure or malfunction, or any *
+* and all other commercial damages or losses, even if such party *
+* shall have been informed of the possibility of such damages. This *
+* limitation of liability shall not apply to liability for death or *
+* personal injury resulting from such party's negligence to the *
+* extent applicable law prohibits such limitation. Some *
+* jurisdictions do not allow the exclusion or limitation of *
+* incidental or consequential damages, so this exclusion and *
+* limitation may not apply to You. *
+* *
+************************************************************************
+
+8. Litigation
+-------------
+
+Any litigation relating to this License may be brought only in the
+courts of a jurisdiction where the defendant maintains its principal
+place of business and such litigation shall be governed by laws of that
+jurisdiction, without reference to its conflict-of-law provisions.
+Nothing in this Section shall prevent a party's ability to bring
+cross-claims or counter-claims.
+
+9. Miscellaneous
+----------------
+
+This License represents the complete agreement concerning the subject
+matter hereof. If any provision of this License is held to be
+unenforceable, such provision shall be reformed only to the extent
+necessary to make it enforceable. Any law or regulation which provides
+that the language of a contract shall be construed against the drafter
+shall not be used to construe this License against a Contributor.
+
+10. Versions of the License
+---------------------------
+
+10.1. New Versions
+
+Mozilla Foundation is the license steward. Except as provided in Section
+10.3, no one other than the license steward has the right to modify or
+publish new versions of this License. Each version will be given a
+distinguishing version number.
+
+10.2. Effect of New Versions
+
+You may distribute the Covered Software under the terms of the version
+of the License under which You originally received the Covered Software,
+or under the terms of any subsequent version published by the license
+steward.
+
+10.3. Modified Versions
+
+If you create software not governed by this License, and you want to
+create a new license for such software, you may create and use a
+modified version of this License if you rename the license and remove
+any references to the name of the license steward (except to note that
+such modified license differs from this License).
+
+10.4. Distributing Source Code Form that is Incompatible With Secondary
+Licenses
+
+If You choose to distribute Source Code Form that is Incompatible With
+Secondary Licenses under the terms of this version of the License, the
+notice described in Exhibit B of this License must be attached.
+
+Exhibit A - Source Code Form License Notice
+-------------------------------------------
+
+This Source Code Form is subject to the terms of the Mozilla Public
+License, v. 2.0. If a copy of the MPL was not distributed with this
+file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+If it is not possible or desirable to put the notice in a particular
+file, then You may include the notice in a location (such as a LICENSE
+file in a relevant directory) where a recipient would be likely to look
+for such a notice.
+
+You may add additional accurate notices of copyright ownership.
+
+Exhibit B - "Incompatible With Secondary Licenses" Notice
+---------------------------------------------------------
+
+This Source Code Form is "Incompatible With Secondary Licenses", as
+defined by the Mozilla Public License, v. 2.0.
+
diff --git a/third_party/rust/runloop/README.md b/third_party/rust/runloop/README.md
new file mode 100644
index 000000000000..8b9508b93be0
--- /dev/null
+++ b/third_party/rust/runloop/README.md
@@ -0,0 +1,88 @@
+# runloop [![Crates.io](https://img.shields.io/crates/v/runloop.svg)](https://crates.io/crates/runloop) [![Build Status](https://travis-ci.org/ttaubert/rust-runloop.svg?branch=master)](https://travis-ci.org/ttaubert/rust-runloop) [![License](https://img.shields.io/badge/license-MPL2-blue.svg?style=flat)](LICENSE)
+
+This crate provides a cancelable `RunLoop` to simplify writing non-blocking
+polling threads.
+
+## Usage
+
+The closure passed to `RunLoop::new()` or `RunLoop::new_with_timeout()` will be
+called once and is executed in the newly spawned thread. It should periodically
+check, via the given callback argument named `alive` in the below examples,
+whether the runloop was requested to terminate.
+
+`RunLoop::alive()` allows the owning thread to check whether the runloop is
+still alive. This can be useful for debugging (e.g. assertions) or early
+returns on failure in the passed closure.
+
+`RunLoop::cancel()` will request the runloop to terminate. If the runloop is
+still active it will join the thread and block. If the runloop already
+terminated on its own this will be a no-op.
+
+### Example: An endless runloop
+
+A runloop does not have to terminate on its own, it can wait until the
+`cancel()` method is called.
+
+```rust
+// This runloop runs until we stop it.
+let rloop = RunLoop::new(|alive| {
+    while alive() { /* endless loop */ }
+})?;
+
+// Loop a few times.
+thread::sleep_ms(500);
+assert!(rloop.alive());
+
+// This will cause `alive()` to return false
+// and block until the thread was joined.
+rloop.cancel();
+```
+
+### Example: A runloop with a timeout
+
+Creating a runloop via `new_with_timeout()` ensures that `alive()` returns
+`false` after the given duration.
+
+```rust
+// This runloop will time out after 10ms.
+let rloop = RunLoop::new_with_timeout(|alive| {
+    while alive() { /* endless loop */ }
+}, 10)?;
+
+// Wait for the timeout.
+while rloop.alive() { /* loop */ }
+
+// This won't block anymore, it's a no-op.
+// The runloop has already terminated.
+rloop.cancel();
+```
+
+### Example: A runloop with channels
+
+As a runloop will run the given closure in a newly spawned thread it requires
+channels and similar utilities to communicate back to the owning thread.
+
+```rust
+let (tx, rx) = channel();
+
+// This runloop will send a lot of numbers.
+let rloop = RunLoop::new(move |alive| {
+    let mut counter = 0u64;
+    while alive() {
+        tx.send(counter).unwrap();
+        counter += 1;
+    }
+})?;
+
+// Wait until we receive a specific number.
+while rx.recv().unwrap() < 50 { /* loop */ }
+
+// We've seen enough.
+rloop.cancel();
+```
+
+## License
+
+`runloop` is distributed under the terms of the Mozilla Public License, v. 2.0.
+
+See [LICENSE](LICENSE) for details.
diff --git a/third_party/rust/runloop/rustfmt.toml b/third_party/rust/runloop/rustfmt.toml
new file mode 100644
index 000000000000..ed37b0c63a5f
--- /dev/null
+++ b/third_party/rust/runloop/rustfmt.toml
@@ -0,0 +1,2 @@
+comment_width = 200
+wrap_comments = true
diff --git a/dom/webauthn/u2f-hid-rs/src/runloop.rs b/third_party/rust/runloop/src/lib.rs
similarity index 69%
rename from dom/webauthn/u2f-hid-rs/src/runloop.rs
rename to third_party/rust/runloop/src/lib.rs
index 39cdcaee3060..d705e605d021 100644
--- a/dom/webauthn/u2f-hid-rs/src/runloop.rs
+++ b/third_party/rust/runloop/src/lib.rs
@@ -5,8 +5,7 @@
 use std::io;
 use std::sync::{Arc, Mutex, Weak};
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::thread;
-use std::thread::JoinHandle;
+use std::thread::{Builder, JoinHandle};
 use std::time::{Duration, Instant};
 
 struct Canary {
@@ -28,7 +27,15 @@ pub struct RunLoop {
 }
 
 impl RunLoop {
-    pub fn new<F, T>(fun: F, timeout_ms: u64) -> io::Result<Self>
+    pub fn new<F, T>(fun: F) -> io::Result<Self>
+    where
+        F: FnOnce(&Fn() -> bool) -> T,
+        F: Send + 'static,
+    {
+        Self::new_with_timeout(fun, 0 /* no timeout */)
+    }
+
+    pub fn new_with_timeout<F, T>(fun: F, timeout_ms: u64) -> io::Result<Self>
     where
         F: FnOnce(&Fn() -> bool) -> T,
         F: Send + 'static,
@@ -37,7 +44,7 @@ impl RunLoop {
         let flag_ = flag.clone();
 
         // Spawn the run loop thread.
-        let thread = thread::Builder::new().spawn(move || {
+        let thread = Builder::new().spawn(move || {
             let timeout = Duration::from_millis(timeout_ms);
             let start = Instant::now();
 
@@ -97,21 +104,22 @@ impl RunLoop {
 #[cfg(test)]
 mod tests {
     use std::sync::{Arc, Barrier};
+    use std::sync::mpsc::channel;
 
     use super::RunLoop;
 
     #[test]
     fn test_empty() {
         // Create a runloop that exits right away.
-        let thread = RunLoop::new(move |_| {}, 0).unwrap();
-        while thread.alive() { /* wait */ }
-        thread.cancel(); // noop
+        let rloop = RunLoop::new(|_| {}).unwrap();
+        while rloop.alive() { /* wait */ }
+        rloop.cancel(); // noop
     }
 
     #[test]
     fn test_cancel_early() {
         // Create a runloop and cancel it before the thread spawns.
-        RunLoop::new(|alive| assert!(!alive()), 0).unwrap().cancel();
+        RunLoop::new(|alive| assert!(!alive())).unwrap().cancel();
     }
 
     #[test]
@@ -120,27 +128,41 @@ mod tests {
         let b = barrier.clone();
 
         // Create a runloop that never exits.
-        let thread = RunLoop::new(
-            move |alive| {
-                b.wait();
-                while alive() { /* loop */ }
-            },
-            0,
-        ).unwrap();
+        let rloop = RunLoop::new(move |alive| {
+            b.wait();
+            while alive() { /* loop */ }
+        }).unwrap();
 
         barrier.wait();
-        assert!(thread.alive());
-        thread.cancel();
-        assert!(!thread.alive());
+        assert!(rloop.alive());
+        rloop.cancel();
+        assert!(!rloop.alive());
     }
 
     #[test]
     fn test_timeout() {
-        // Create a runloop that never exits, but times out after a second.
-        let thread = RunLoop::new(|alive| while alive() {}, 1).unwrap();
+        // Create a runloop that never exits, but times out after 1ms.
+        let rloop = RunLoop::new_with_timeout(|alive| while alive() {}, 1).unwrap();
 
-        while thread.alive() { /* wait */ }
-        assert!(!thread.alive());
-        thread.cancel(); // noop
+        while rloop.alive() { /* wait */ }
+        assert!(!rloop.alive());
+        rloop.cancel(); // noop
+    }
+
+    #[test]
+    fn test_channel() {
+        let (tx, rx) = channel();
+
+        // A runloop that sends data via a channel.
+        let rloop = RunLoop::new(move |alive| while alive() {
+            tx.send(0u8).unwrap();
+        }).unwrap();
+
+        // Wait until the data arrives.
+        assert_eq!(rx.recv().unwrap(), 0u8);
+
+        assert!(rloop.alive());
+        rloop.cancel();
+        assert!(!rloop.alive());
     }
 }
diff --git a/toolkit/library/gtest/rust/Cargo.lock b/toolkit/library/gtest/rust/Cargo.lock
index 6c84a198c9db..483ba9a2fa60 100644
--- a/toolkit/library/gtest/rust/Cargo.lock
+++ b/toolkit/library/gtest/rust/Cargo.lock
@@ -1127,6 +1127,11 @@ name = "regex-syntax"
 version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "runloop"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "rust_url_capi"
 version = "0.0.1"
@@ -1471,6 +1476,7 @@ dependencies = [
  "libudev 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
+ "runloop 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1738,6 +1744,7 @@ dependencies = [
 "checksum redox_syscall 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)" = "8dd35cc9a8bdec562c757e3d43c1526b5c6d2653e23e2315065bc25556550753"
 "checksum regex 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "4278c17d0f6d62dfef0ab00028feb45bd7d2102843f80763474eeb1be8a10c01"
 "checksum regex-syntax 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "2f9191b1f57603095f105d317e375d19b1c9c5c3185ea9633a99a6dcbed04457"
+"checksum runloop 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5d79b4b604167921892e84afbbaad9d5ad74e091bf6c511d9dbfb0593f09fabd"
 "checksum rustc-demangle 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "3058a43ada2c2d0b92b3ae38007a2d0fa5e9db971be260e0171408a4ff471c95"
 "checksum rustc-serialize 0.3.22 (registry+https://github.com/rust-lang/crates.io-index)" = "237546c689f20bb44980270c73c3b9edd0891c1be49cc1274406134a66d3957b"
 "checksum same-file 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "d931a44fdaa43b8637009e7632a02adc4f2b2e0733c08caa4cf00e8da4a117a7"
diff --git a/toolkit/library/rust/Cargo.lock b/toolkit/library/rust/Cargo.lock
index 0a31f943ce9a..03433913bce8 100644
--- a/toolkit/library/rust/Cargo.lock
+++ b/toolkit/library/rust/Cargo.lock
@@ -1114,6 +1114,11 @@ name = "regex-syntax"
 version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "runloop"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "rust_url_capi"
 version = "0.0.1"
@@ -1458,6 +1463,7 @@ dependencies = [
  "libudev 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
+ "runloop 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1725,6 +1731,7 @@ dependencies = [
 "checksum redox_syscall 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)" = "8dd35cc9a8bdec562c757e3d43c1526b5c6d2653e23e2315065bc25556550753"
 "checksum regex 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "4278c17d0f6d62dfef0ab00028feb45bd7d2102843f80763474eeb1be8a10c01"
 "checksum regex-syntax 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "2f9191b1f57603095f105d317e375d19b1c9c5c3185ea9633a99a6dcbed04457"
+"checksum runloop 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5d79b4b604167921892e84afbbaad9d5ad74e091bf6c511d9dbfb0593f09fabd"
 "checksum rustc-demangle 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "3058a43ada2c2d0b92b3ae38007a2d0fa5e9db971be260e0171408a4ff471c95"
 "checksum rustc-serialize 0.3.22 (registry+https://github.com/rust-lang/crates.io-index)" = "237546c689f20bb44980270c73c3b9edd0891c1be49cc1274406134a66d3957b"
 "checksum same-file 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "d931a44fdaa43b8637009e7632a02adc4f2b2e0733c08caa4cf00e8da4a117a7"