Eliminate MediaPlayer & MediaPlayerClient abstractions

Source/platform/blink_platform.gypi

 {
   'includes': [
     'platform_generated.gypi',
   ],
   'variables': {
     'platform_files': [
       'AsyncFileSystemCallbacks.h',
       'CalculationValue.h',
       'CheckedInt.h',
       'Clock.cpp',
@@ skipping 616 matching lines @@
       'graphics/filters/SpotLightSource.cpp',
       'graphics/filters/SpotLightSource.h',
       'graphics/gpu/AcceleratedImageBufferSurface.cpp',
       'graphics/gpu/AcceleratedImageBufferSurface.h',
       'graphics/gpu/DrawingBuffer.cpp',
       'graphics/gpu/DrawingBuffer.h',
       'graphics/gpu/Extensions3DUtil.cpp',
       'graphics/gpu/Extensions3DUtil.h',
       'graphics/gpu/WebGLImageConversion.cpp',
       'graphics/gpu/WebGLImageConversion.h',
-      'graphics/media/MediaPlayer.cpp',
-      'graphics/media/MediaPlayer.h',
       'graphics/paint/CachedDisplayItem.h',
       'graphics/paint/ClipDisplayItem.cpp',
       'graphics/paint/ClipDisplayItem.h',
       'graphics/paint/ClipPathDisplayItem.cpp',
       'graphics/paint/ClipPathDisplayItem.h',
       'graphics/paint/ClipPathRecorder.cpp',
       'graphics/paint/ClipPathRecorder.h',
       'graphics/paint/ClipRecorder.cpp',
       'graphics/paint/ClipRecorder.h',
       'graphics/paint/DisplayItem.cpp',
@@ skipping 357 matching lines @@
       'image-decoders/webp/WEBPImageDecoderTest.cpp',
     ],
     'platform_unittest_support_files': [
       'testing/URLTestHelpers.cpp',
       'testing/URLTestHelpers.h',
       'testing/UnitTestHelpers.cpp',
       'testing/UnitTestHelpers.h',
     ],
   },
 }