Implement enumerateDevices() according to spec.

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 90 matching lines @@
       'indexeddb/IDBRequest.idl',
       'indexeddb/IDBTransaction.idl',
       'indexeddb/IDBVersionChangeEvent.idl',
       'mediasource/MediaSource.idl',
       'mediasource/SourceBuffer.idl',
       'mediasource/SourceBufferList.idl',
       'mediasource/TrackDefault.idl',
       'mediasource/TrackDefaultList.idl',
       'mediasource/VideoPlaybackQuality.idl',
       'mediastream/MediaDeviceInfo.idl',
-      'mediastream/MediaDeviceInfoCallback.idl',
+      'mediastream/MediaDevices.idl',
       'mediastream/MediaStream.idl',
       'mediastream/MediaStreamEvent.idl',
       'mediastream/MediaStreamTrack.idl',
       'mediastream/MediaStreamTrackEvent.idl',
       'mediastream/MediaStreamTrackSourcesCallback.idl',
       'mediastream/NavigatorUserMediaError.idl',
       'mediastream/NavigatorUserMediaErrorCallback.idl',
       'mediastream/NavigatorUserMediaSuccessCallback.idl',
       'mediastream/RTCDTMFSender.idl',
       'mediastream/RTCDTMFToneChangeEvent.idl',
@@ skipping 147 matching lines @@
       'gamepad/NavigatorGamepad.idl',
       'geofencing/ServiceWorkerGlobalScopeGeofencing.idl',
       'geofencing/ServiceWorkerRegistrationGeofencing.idl',
       'geofencing/WorkerNavigatorGeofencing.idl',
       'geolocation/NavigatorGeolocation.idl',
       'indexeddb/WindowIndexedDatabase.idl',
       'indexeddb/WorkerGlobalScopeIndexedDatabase.idl',
       'mediasource/HTMLVideoElementMediaSource.idl',
       'mediasource/URLMediaSource.idl',
       'mediastream/NavigatorMediaStream.idl',
+      'mediastream/NavigatorUserMedia.idl',
       'mediastream/URLMediaStream.idl',
       'mediastream/WindowMediaStream.idl',
       'navigatorconnect/NavigatorConnect.idl',
       'navigatorconnect/ServiceWorkerGlobalScopeNavigatorConnect.idl',
       'navigatorconnect/WorkerNavigatorConnect.idl',
       'navigatorcontentutils/NavigatorContentUtils.idl',
       'netinfo/NavigatorNetworkInformation.idl',
       'netinfo/WorkerNavigatorNetworkInformation.idl',
       'notifications/ServiceWorkerGlobalScopeNotifications.idl',
       'notifications/ServiceWorkerRegistrationNotifications.idl',
@@ skipping 631 matching lines @@
       'mediasource/TrackDefaultList.cpp',
       'mediasource/TrackDefaultList.h',
       'mediasource/URLMediaSource.cpp',
       'mediasource/URLMediaSource.h',
       'mediasource/VideoPlaybackQuality.cpp',
       'mediasource/VideoPlaybackQuality.h',
       'mediastream/MediaConstraintsImpl.cpp',
       'mediastream/MediaConstraintsImpl.h',
       'mediastream/MediaDeviceInfo.cpp',
       'mediastream/MediaDeviceInfo.h',
-      'mediastream/MediaDeviceInfoCallback.h',
+      'mediastream/MediaDevices.cpp',
+      'mediastream/MediaDevices.h',
       'mediastream/MediaDevicesRequest.cpp',
       'mediastream/MediaDevicesRequest.h',
       'mediastream/MediaStream.cpp',
       'mediastream/MediaStream.h',
       'mediastream/MediaStreamEvent.cpp',
       'mediastream/MediaStreamEvent.h',
       'mediastream/MediaStreamRegistry.cpp',
       'mediastream/MediaStreamRegistry.h',
       'mediastream/MediaStreamTrack.cpp',
       'mediastream/MediaStreamTrack.h',
       'mediastream/MediaStreamTrackEvent.cpp',
       'mediastream/MediaStreamTrackEvent.h',
       'mediastream/MediaStreamTrackSourcesCallback.h',
       'mediastream/MediaStreamTrackSourcesRequestImpl.cpp',
       'mediastream/MediaStreamTrackSourcesRequestImpl.h',
       'mediastream/NavigatorMediaStream.cpp',
       'mediastream/NavigatorMediaStream.h',
+      'mediastream/NavigatorUserMedia.cpp',
+      'mediastream/NavigatorUserMedia.h',
       'mediastream/NavigatorUserMediaError.cpp',
       'mediastream/NavigatorUserMediaError.h',
       'mediastream/NavigatorUserMediaErrorCallback.h',
       'mediastream/NavigatorUserMediaSuccessCallback.h',
       'mediastream/RTCDTMFSender.cpp',
       'mediastream/RTCDTMFSender.h',
       'mediastream/RTCDTMFToneChangeEvent.cpp',
       'mediastream/RTCDTMFToneChangeEvent.h',
       'mediastream/RTCDataChannel.cpp',
       'mediastream/RTCDataChannel.h',
@@ skipping 501 matching lines @@
       'webaudio/AudioBasicProcessorHandlerTest.cpp',
       'webaudio/ConvolverNodeTest.cpp',
       'webaudio/DynamicsCompressorNodeTest.cpp',
       'webaudio/ScriptProcessorNodeTest.cpp',
       'webaudio/StereoPannerNodeTest.cpp',
       'websockets/DOMWebSocketTest.cpp',
       'websockets/DocumentWebSocketChannelTest.cpp',
     ],
   },
 }