Remove redundant definition of Spatializer abstract class

third_party/WebKit/Source/platform/blink_platform.gypi

 {
   'includes': [
     'platform_generated.gypi',
   ],
   'variables': {
     'platform_files': [
       'AsyncFileSystemCallbacks.h',
       'CalculationValue.h',
       'CheckedInt.h',
       'ContentDecryptionModuleResult.h',
@@ skipping 243 matching lines @@
       'audio/ReverbAccumulationBuffer.cpp',
       'audio/ReverbAccumulationBuffer.h',
       'audio/ReverbConvolver.cpp',
       'audio/ReverbConvolver.h',
       'audio/ReverbConvolverStage.cpp',
       'audio/ReverbConvolverStage.h',
       'audio/ReverbInputBuffer.cpp',
       'audio/ReverbInputBuffer.h',
       'audio/SincResampler.cpp',
       'audio/SincResampler.h',
-      'audio/Spatializer.cpp',
-      'audio/Spatializer.h',
       'audio/StereoPanner.cpp',
       'audio/StereoPanner.h',
       'audio/UpSampler.cpp',
       'audio/UpSampler.h',
       'audio/VectorMath.cpp',
       'audio/VectorMath.h',
       'audio/ZeroPole.cpp',
       'audio/ZeroPole.h',
       'audio/android/FFTFrameOpenMAXDLAndroid.cpp',
       'audio/ffmpeg/FFTFrameFFMPEG.cpp',
@@ skipping 1180 matching lines @@
       ['use_default_render_theme==1',
         {
           'platform_test_files': [
             'scroll/ScrollbarThemeAuraTest.cpp',
           ],
         }
       ],
     ],
   },
 }