MediaStream API: Implement Navigator.getMediaDevices

Source/web/web.gypi

 {
   'variables': {
     'web_files': [
       'ApplicationCacheHost.cpp',
       'ApplicationCacheHostInternal.h',
       'AssertMatchingEnums.cpp',
       'AssociatedURLLoader.cpp',
       'AssociatedURLLoader.h',
       'BackForwardClientImpl.cpp',
       'BackForwardClientImpl.h',
@@ skipping 167 matching lines @@
       'WebInputEventFactoryGtk.cpp',
       'WebInputEventFactoryMac.mm',
       'WebInputEventFactoryWin.cpp',
       'WebInputEventConversion.cpp',
       'WebInputEventConversion.h',
       'WebKit.cpp',
       'WebLabelElement.cpp',
       'WebLeakDetector.cpp',
       'WebMIDIClientMock.cpp',
       'WebMIDIPermissionRequest.cpp',
+      'WebMediaDevicesRequest.cpp',
       'WebMediaPlayerClientImpl.cpp',
       'WebMediaPlayerClientImpl.h',
       'WebMediaStreamRegistry.cpp',
       'WebNetworkStateNotifier.cpp',
       'WebNode.cpp',
       'WebNodeCollection.cpp',
       'WebNodeList.cpp',
       'WebNotification.cpp',
       'WebOptionElement.cpp',
       'WebPagePopupImpl.cpp',
@@ skipping 171 matching lines @@
         {
           'web_unittest_files': [
             'tests/KeyCodeConversionTestGtk.cpp',
             'tests/WebInputEventFactoryTestGtk.cpp',
           ],
         }
       ],
     ],
   },
 }