Presentation API: implement .getAvalability() (Blink side).

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 129 matching lines @@
       'netinfo/NetworkInformation.idl',
       'notifications/Notification.idl',
       'notifications/NotificationEvent.idl',
       'notifications/NotificationPermissionCallback.idl',
       'permissions/Permissions.idl',
       'permissions/PermissionStatus.idl',
       'plugins/MimeType.idl',
       'plugins/MimeTypeArray.idl',
       'plugins/Plugin.idl',
       'plugins/PluginArray.idl',
-      'presentation/AvailableChangeEvent.idl',
       'presentation/DefaultSessionStartEvent.idl',
       'presentation/Presentation.idl',
+      'presentation/PresentationAvailability.idl',
       'presentation/PresentationSession.idl',
       'push_messaging/PushEvent.idl',
       'push_messaging/PushManager.idl',
       'push_messaging/PushMessageData.idl',
       'push_messaging/PushSubscription.idl',
       'quota/DeprecatedStorageInfo.idl',
       'quota/DeprecatedStorageQuota.idl',
       'quota/StorageErrorCallback.idl',
       'quota/StorageInfo.idl',
       'quota/StorageQuota.idl',
@@ skipping 161 matching lines @@
       'gamepad/GamepadEvent.idl',
       'geofencing/GeofencingEvent.idl',
       'indexeddb/IDBVersionChangeEvent.idl',
       'mediastream/MediaStreamEvent.idl',
       'mediastream/MediaStreamTrackEvent.idl',
       'mediastream/RTCDTMFToneChangeEvent.idl',
       'mediastream/RTCDataChannelEvent.idl',
       'mediastream/RTCIceCandidateEvent.idl',
       'navigatorconnect/CrossOriginConnectEvent.idl',
       'notifications/NotificationEvent.idl',
-      'presentation/AvailableChangeEvent.idl',
       'presentation/DefaultSessionStartEvent.idl',
       'push_messaging/PushEvent.idl',
       'serviceworkers/ExtendableEvent.idl',
       'serviceworkers/FetchEvent.idl',
       'speech/SpeechRecognitionError.idl',
       'speech/SpeechRecognitionEvent.idl',
       'speech/SpeechSynthesisEvent.idl',
       'storage/StorageEvent.idl',
       'webaudio/AudioProcessingEvent.idl',
       'webaudio/OfflineAudioCompletionEvent.idl',
@@ skipping 35 matching lines @@
       'mediastream/RTCIceCandidateInit.idl',
       'mediastream/RTCSessionDescriptionInit.idl',
       'navigatorconnect/ServicePortConnectOptions.idl',
       'navigatorconnect/ServicePortMatchOptions.idl',
       'notifications/GetNotificationOptions.idl',
       'notifications/NotificationEventInit.idl',
       'notifications/NotificationOptions.idl',
       'permissions/MidiPermissionDescriptor.idl',
       'permissions/PermissionDescriptor.idl',
       'permissions/PushPermissionDescriptor.idl',
-      'presentation/AvailableChangeEventInit.idl',
       'presentation/DefaultSessionStartEventInit.idl',
       'push_messaging/PushEventInit.idl',
       'push_messaging/PushSubscriptionOptions.idl',
       'serviceworkers/ClientQueryOptions.idl',
       'serviceworkers/ExtendableEventInit.idl',
       'serviceworkers/FetchEventInit.idl',
       'serviceworkers/RegistrationOptions.idl',
       'speech/SpeechRecognitionErrorInit.idl',
       'speech/SpeechRecognitionEventInit.idl',
       'storage/StorageEventInit.idl',
@@ skipping 86 matching lines @@
       '<(blink_modules_output_dir)/notifications/NotificationEventInit.cpp',
       '<(blink_modules_output_dir)/notifications/NotificationEventInit.h',
       '<(blink_modules_output_dir)/notifications/NotificationOptions.cpp',
       '<(blink_modules_output_dir)/notifications/NotificationOptions.h',
       '<(blink_modules_output_dir)/permissions/MidiPermissionDescriptor.cpp',
       '<(blink_modules_output_dir)/permissions/MidiPermissionDescriptor.h',
       '<(blink_modules_output_dir)/permissions/PermissionDescriptor.cpp',
       '<(blink_modules_output_dir)/permissions/PermissionDescriptor.h',
       '<(blink_modules_output_dir)/permissions/PushPermissionDescriptor.cpp',
       '<(blink_modules_output_dir)/permissions/PushPermissionDescriptor.h',
-      '<(blink_modules_output_dir)/presentation/AvailableChangeEventInit.cpp',
-      '<(blink_modules_output_dir)/presentation/AvailableChangeEventInit.h',
       '<(blink_modules_output_dir)/presentation/DefaultSessionStartEventInit.cpp',
       '<(blink_modules_output_dir)/presentation/DefaultSessionStartEventInit.h',
       '<(blink_modules_output_dir)/push_messaging/PushEventInit.cpp',
       '<(blink_modules_output_dir)/push_messaging/PushEventInit.h',
       '<(blink_modules_output_dir)/push_messaging/PushSubscriptionOptions.cpp',
       '<(blink_modules_output_dir)/push_messaging/PushSubscriptionOptions.h',
       '<(blink_modules_output_dir)/serviceworkers/ClientQueryOptions.cpp',
       '<(blink_modules_output_dir)/serviceworkers/ClientQueryOptions.h',
       '<(blink_modules_output_dir)/serviceworkers/ExtendableEventInit.cpp',
       '<(blink_modules_output_dir)/serviceworkers/ExtendableEventInit.h',
@@ skipping 567 matching lines @@
       'plugins/DOMMimeTypeArray.cpp',
       'plugins/DOMMimeTypeArray.h',
       'plugins/DOMPlugin.cpp',
       'plugins/DOMPlugin.h',
       'plugins/DOMPluginArray.cpp',
       'plugins/DOMPluginArray.h',
       'plugins/NavigatorPlugins.cpp',
       'plugins/NavigatorPlugins.h',
       'plugins/PluginOcclusionSupport.cpp',
       'plugins/PluginOcclusionSupport.h',
-      'presentation/AvailableChangeEvent.cpp',
-      'presentation/AvailableChangeEvent.h',
       'presentation/DefaultSessionStartEvent.cpp',
       'presentation/DefaultSessionStartEvent.h',
       'presentation/NavigatorPresentation.cpp',
       'presentation/NavigatorPresentation.h',
       'presentation/Presentation.cpp',
       'presentation/Presentation.h',
+      'presentation/PresentationAvailability.cpp',
+      'presentation/PresentationAvailability.h',
       'presentation/PresentationController.cpp',
       'presentation/PresentationController.h',
       'presentation/PresentationError.cpp',
       'presentation/PresentationError.h',
       'presentation/PresentationSession.cpp',
       'presentation/PresentationSession.h',
       'presentation/PresentationSessionClientCallbacks.cpp',
       'presentation/PresentationSessionClientCallbacks.h',
       'push_messaging/PushController.cpp',
       'push_messaging/PushController.h',
@@ skipping 405 matching lines @@
       'webaudio/AudioBasicProcessorHandlerTest.cpp',
       'webaudio/ConvolverNodeTest.cpp',
       'webaudio/DynamicsCompressorNodeTest.cpp',
       'webaudio/ScriptProcessorNodeTest.cpp',
       'webaudio/StereoPannerNodeTest.cpp',
       'websockets/DOMWebSocketTest.cpp',
       'websockets/DocumentWebSocketChannelTest.cpp',
     ],
   },
 }