[LoaderTest] Add unit tests for Document/WorkerThreadableLoader

third_party/WebKit/Source/core/core.gypi

 {
     'includes': [
         'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/KeyframeEffect.idl',
             'animation/EffectModel.idl',
             'animation/AnimationEffectReadOnly.idl',
@@ skipping 4019 matching lines @@
             'layout/PaginationTest.cpp',
             'layout/PaintContainmentTest.cpp',
             'layout/ScrollAnchorTest.cpp',
             'layout/compositing/CompositedLayerMappingTest.cpp',
             'layout/shapes/BoxShapeTest.cpp',
             'loader/DocumentLoadTimingTest.cpp',
             'loader/FrameFetchContextTest.cpp',
             'loader/LinkHeaderTest.cpp',
             'loader/LinkLoaderTest.cpp',
             'loader/MixedContentCheckerTest.cpp',
+            'loader/ThreadableLoaderTest.cpp',
             'origin_trials/OriginTrialContextTest.cpp',
             'page/ChromeClientTest.cpp',
             'page/ContextMenuControllerTest.cpp',
             'page/EventSourceParserTest.cpp',
             'page/FocusControllerTest.cpp',
             'page/NetworkStateNotifierTest.cpp',
             'page/PagePopupClientTest.cpp',
             'page/PrintContextTest.cpp',
             'page/WindowFeaturesTest.cpp',
             'page/scrolling/ScrollStateTest.cpp',
@@ skipping 10 matching lines @@
             'streams/ReadableStreamReaderTest.cpp',
             'streams/ReadableStreamTest.cpp',
             'style/ComputedStyleTest.cpp',
             'style/OutlineValueTest.cpp',
             'style/SVGComputedStyleTest.cpp',
             'svg/SVGPathParserTest.cpp',
             'svg/UnsafeSVGAttributeSanitizationTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
+            'workers/WorkerThreadTestHelper.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }