Add WebUSB bindings and client interface [part 2]

Source/modules/modules.gypi

 {
   'includes': [
     '../core/core_generated.gypi',
     'modules_generated.gypi',
   ],
   'variables': {
     # Experimental hooks for embedder to provide extra IDL and source files.
     #
     # Note: this is not a supported API. If you rely on this, you will be broken
     # from time to time as the code generator changes in backward incompatible
@@ skipping 1666 matching lines @@
       'websockets/WebSocketFrame.h',
       'websockets/WorkerWebSocketChannel.cpp',
       'websockets/WorkerWebSocketChannel.h',
       'webusb/NavigatorUSB.cpp',
       'webusb/NavigatorUSB.h',
       'webusb/USB.cpp',
       'webusb/USB.h',
       'webusb/USBController.cpp',
       'webusb/USBController.h',
       'webusb/USBDevice.h',
+      'webusb/USBError.cpp',
+      'webusb/USBError.h',
     ],
     # 'partial interface' or target (right side of) 'implements'
     'modules_testing_dependency_idl_files' : [
       'accessibility/testing/InternalsAccessibility.idl',
       'geolocation/testing/InternalsGeolocation.idl',
       'navigatorcontentutils/testing/InternalsNavigatorContentUtils.idl',
       'serviceworkers/testing/InternalsServiceWorker.idl',
       'speech/testing/InternalsSpeechSynthesis.idl',
       'vibration/testing/InternalsVibration.idl',
       'webaudio/testing/InternalsWebAudio.idl',
@@ skipping 47 matching lines @@
       'webaudio/AudioBasicProcessorHandlerTest.cpp',
       'webaudio/ConvolverNodeTest.cpp',
       'webaudio/DynamicsCompressorNodeTest.cpp',
       'webaudio/ScriptProcessorNodeTest.cpp',
       'webaudio/StereoPannerNodeTest.cpp',
       'websockets/DOMWebSocketTest.cpp',
       'websockets/DocumentWebSocketChannelTest.cpp',
     ],
   },
 }