Added plumbing for the availablechange event from Blink to WebPresentationClient.

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 107 matching lines @@
       'mediastream/SourceInfo.idl',
       'navigatorconnect/CrossOriginConnectEvent.idl',
       'navigatorconnect/CrossOriginServiceWorkerClient.idl',
       'netinfo/NetworkInformation.idl',
       'notifications/Notification.idl',
       'notifications/NotificationEvent.idl',
       'notifications/NotificationPermissionCallback.idl',
       'performance/WorkerPerformance.idl',
       'permissions/Permissions.idl',
       'permissions/PermissionStatus.idl',
+      'presentation/AvailableChangeEvent.idl',
       'presentation/Presentation.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',
@@ skipping 144 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',
       'push_messaging/PushEvent.idl',
       'serviceworkers/ExtendableEvent.idl',
       'serviceworkers/FetchEvent.idl',
       'serviceworkers/InstallEvent.idl',
       'speech/SpeechRecognitionError.idl',
       'speech/SpeechRecognitionEvent.idl',
       'speech/SpeechSynthesisEvent.idl',
       'webaudio/AudioProcessingEvent.idl',
       'webaudio/OfflineAudioCompletionEvent.idl',
       'webmidi/MIDIConnectionEvent.idl',
@@ skipping 14 matching lines @@
       'geolocation/PositionOptions.idl',
       'indexeddb/IDBIndexParameters.idl',
       'indexeddb/IDBObjectStoreParameters.idl',
       'indexeddb/IDBVersionChangeEventInit.idl',
       'mediastream/MediaStreamEventInit.idl',
       'mediastream/RTCDTMFToneChangeEventInit.idl',
       'mediastream/RTCIceCandidateInit.idl',
       'mediastream/RTCSessionDescriptionInit.idl',
       'notifications/NotificationEventInit.idl',
       'notifications/NotificationOptions.idl',
+      'presentation/AvailableChangeEventInit.idl',
       'push_messaging/PushEventInit.idl',
       'serviceworkers/CacheQueryOptions.idl',
       'serviceworkers/ClientQueryOptions.idl',
       'serviceworkers/ExtendableEventInit.idl',
       'serviceworkers/InstallEventInit.idl',
       'serviceworkers/RegistrationOptions.idl',
       'speech/SpeechRecognitionErrorInit.idl',
       'speech/SpeechRecognitionEventInit.idl',
       'webmidi/MIDIConnectionEventInit.idl',
       'webmidi/MIDIMessageEventInit.idl',
@@ skipping 45 matching lines @@
       '<(blink_modules_output_dir)/mediastream/RTCDTMFToneChangeEventInit.cpp',
       '<(blink_modules_output_dir)/mediastream/RTCDTMFToneChangeEventInit.h',
       '<(blink_modules_output_dir)/mediastream/RTCIceCandidateInit.cpp',
       '<(blink_modules_output_dir)/mediastream/RTCIceCandidateInit.h',
       '<(blink_modules_output_dir)/mediastream/RTCSessionDescriptionInit.cpp',
       '<(blink_modules_output_dir)/mediastream/RTCSessionDescriptionInit.h',
       '<(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)/presentation/AvailableChangeEventInit.cpp',
+      '<(blink_modules_output_dir)/presentation/AvailableChangeEventInit.h',
       '<(blink_modules_output_dir)/push_messaging/PushEventInit.cpp',
       '<(blink_modules_output_dir)/push_messaging/PushEventInit.h',
       '<(blink_modules_output_dir)/serviceworkers/CacheQueryOptions.cpp',
       '<(blink_modules_output_dir)/serviceworkers/CacheQueryOptions.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',
       '<(blink_modules_output_dir)/serviceworkers/InstallEventInit.cpp',
       '<(blink_modules_output_dir)/serviceworkers/InstallEventInit.h',
@@ skipping 454 matching lines @@
       'notifications/ServiceWorkerRegistrationNotifications.h',
       'performance/SharedWorkerPerformance.cpp',
       'performance/WorkerGlobalScopePerformance.cpp',
       'performance/WorkerGlobalScopePerformance.h',
       'performance/WorkerPerformance.cpp',
       'performance/WorkerPerformance.h',
       'permissions/Permissions.cpp',
       'permissions/Permissions.h',
       'permissions/PermissionStatus.cpp',
       'permissions/PermissionStatus.h',
+      'presentation/AvailableChangeEvent.h',
+      'presentation/AvailableChangeEvent.cpp',
       'presentation/NavigatorPresentation.cpp',
       'presentation/NavigatorPresentation.h',
       'presentation/Presentation.cpp',
       'presentation/Presentation.h',
+      'presentation/PresentationController.cpp',
+      'presentation/PresentationController.h',
       'presentation/PresentationSession.cpp',
       'presentation/PresentationSession.h',
       'push_messaging/PushController.cpp',
       'push_messaging/PushController.h',
       'push_messaging/PushError.cpp',
       'push_messaging/PushError.h',
       'push_messaging/PushEvent.cpp',
       'push_messaging/PushEvent.h',
       'push_messaging/PushManager.cpp',
       'push_messaging/PushManager.h',
@@ skipping 343 matching lines @@
       'indexeddb/IDBKeyPathTest.cpp',
       'indexeddb/IDBRequestTest.cpp',
       'indexeddb/IDBTransactionTest.cpp',
       'serviceworkers/CacheTest.cpp',
       'serviceworkers/ServiceWorkerContainerTest.cpp',
       'websockets/DOMWebSocketTest.cpp',
       'websockets/DocumentWebSocketChannelTest.cpp',
     ],
   },
 }