Enable WebUSB through the Experimental Framework.

third_party/WebKit/LayoutTests/virtual/stable/webexposed/global-interface-listing-expected.txt

Index: third_party/WebKit/LayoutTests/virtual/stable/webexposed/global-interface-listing-expected.txt
diff --git a/third_party/WebKit/LayoutTests/virtual/stable/webexposed/global-interface-listing-expected.txt b/third_party/WebKit/LayoutTests/virtual/stable/webexposed/global-interface-listing-expected.txt
index ab3ee59fd2e1e8c1d2515e80cb59d1d5d50882b9..b44e050cd222f0abaadef0ec7f6d377701c22899 100644
--- a/third_party/WebKit/LayoutTests/virtual/stable/webexposed/global-interface-listing-expected.txt
+++ b/third_party/WebKit/LayoutTests/virtual/stable/webexposed/global-interface-listing-expected.txt
@@ -10,6 +10,7 @@ CONSOLE WARNING: 'webkitIDBFactory' is deprecated. Please use 'IDBFactory' inste
 CONSOLE WARNING: 'webkitIDBDatabase' is deprecated. Please use 'IDBDatabase' instead.
 CONSOLE WARNING: 'webkitIDBCursor' is deprecated. Please use 'IDBCursor' instead.
 CONSOLE WARNING: 'webkitIndexedDB' is deprecated. Please use 'indexedDB' instead.
+CONSOLE ERROR: The 'WebUSB' feature is currently enabled in limited trials. Please see [Phosphor console URL] for information on enabling a trial for your site.
 CONSOLE ERROR: The 'WebBluetooth' feature is currently enabled in limited trials. Please see [Phosphor console URL] for information on enabling a trial for your site.
 CONSOLE WARNING: 'webkitURL' is deprecated. Please use 'URL' instead.
 This test documents all interface attributes and methods on the global window object and element instances.
@@ -3350,6 +3351,7 @@ interface Navigator
     getter product
     getter productSub
     getter serviceWorker
+    getter usb
     getter userAgent
     getter vendor
     getter vendorSub
@@ -6427,6 +6429,18 @@ interface webkitURL
     attribute BluetoothRemoteGATTService
     attribute BluetoothUUID
     attribute GCController
+    attribute USBAlternateInterface
+    attribute USBConfiguration
+    attribute USBConnectionEvent
+    attribute USBDevice
+    attribute USBEndpoint
+    attribute USBInTransferResult
+    attribute USBInterface
+    attribute USBIsochronousInTransferPacket
+    attribute USBIsochronousInTransferResult
+    attribute USBIsochronousOutTransferPacket
+    attribute USBIsochronousOutTransferResult
+    attribute USBOutTransferResult
     attribute accessibilityController
     attribute applicationCache
     attribute caches