[worklets] Split up InProcessWorkerMessagingProxy into a base+worker class.

third_party/WebKit/Source/core/workers/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//third_party/WebKit/Source/core/core.gni")
 
 blink_core_sources("workers") {
   sources = [
     "AbstractWorker.cpp",
     "AbstractWorker.h",
@@ skipping 15 matching lines @@
     "MainThreadWorkletGlobalScope.h",
     "ParentFrameTaskRunners.cpp",
     "ParentFrameTaskRunners.h",
     "SharedWorker.cpp",
     "SharedWorker.h",
     "SharedWorkerGlobalScope.cpp",
     "SharedWorkerGlobalScope.h",
     "SharedWorkerRepositoryClient.h",
     "SharedWorkerThread.cpp",
     "SharedWorkerThread.h",
+    "ThreadedMessagingProxyBase.cpp",
+    "ThreadedMessagingProxyBase.h",
     "ThreadedWorkletGlobalScope.cpp",
     "ThreadedWorkletGlobalScope.h",
     "ThreadedWorkletGlobalScopeProxy.h",
     "Worker.cpp",
     "Worker.h",
     "WorkerBackingThread.cpp",
     "WorkerBackingThread.h",
     "WorkerClients.cpp",
     "WorkerClients.h",
     "WorkerEventQueue.cpp",
@@ skipping 25 matching lines @@
     "WorkletGlobalScope.h",
     "WorkletScriptLoader.cpp",
     "WorkletScriptLoader.h",
   ]
 
   configs += [
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     "//build/config/compiler:no_size_t_to_int_warning",
   ]
 }