[worklets] Introduce ThreadedWorkletMessagingProxy and AnimationWorkletMessagaingProxy.

third_party/WebKit/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 384 matching lines @@
       'canvas2d/ClipList.h',
       'canvas2d/HitRegion.cpp',
       'canvas2d/HitRegion.h',
       'canvas2d/Path2D.h',
       'compositorworker/AbstractAnimationWorkletThread.cpp',
       'compositorworker/AbstractAnimationWorkletThread.h',
       'compositorworker/AnimationWorklet.cpp',
       'compositorworker/AnimationWorklet.h',
       'compositorworker/AnimationWorkletGlobalScope.cpp',
       'compositorworker/AnimationWorkletGlobalScope.h',
+      'compositorworker/AnimationWorkletMessagingProxy.cpp',
+      'compositorworker/AnimationWorkletMessagingProxy.h',
       'compositorworker/AnimationWorkletThread.cpp',
       'compositorworker/AnimationWorkletThread.h',
       'compositorworker/CompositorWorker.cpp',
       'compositorworker/CompositorWorker.h',
       'compositorworker/CompositorWorkerGlobalScope.cpp',
       'compositorworker/CompositorWorkerGlobalScope.h',
       'compositorworker/CompositorWorkerMessagingProxy.cpp',
       'compositorworker/CompositorWorkerMessagingProxy.h',
       'compositorworker/CompositorWorkerThread.cpp',
       'compositorworker/CompositorWorkerThread.h',
@@ skipping 570 matching lines @@
       'screen_orientation/ScreenOrientation.cpp',
       'screen_orientation/ScreenOrientation.h',
       'screen_orientation/ScreenOrientationController.cpp',
       'screen_orientation/ScreenOrientationController.h',
       'screen_orientation/ScreenOrientationDispatcher.cpp',
       'screen_orientation/ScreenOrientationDispatcher.h',
     ],
     # 'partial interface' or target (right side of) 'implements'
   },
 }