Eliminate MediaPlayer & MediaPlayerClient abstractions

Source/web/web.gypi

 {
   'variables': {
     'web_files': [
       'AssertMatchingEnums.cpp',
       'AssociatedURLLoader.cpp',
       'AssociatedURLLoader.h',
       'ChromeClientImpl.cpp',
       'ChromeClientImpl.h',
       'ColorChooserPopupUIController.cpp',
       'ColorChooserPopupUIController.h',
@@ skipping 166 matching lines @@
       'WebInputEventConversion.cpp',
       'WebInputEventConversion.h',
       'WebInputEventFactoryMac.mm',
       'WebKit.cpp',
       'WebLabelElement.cpp',
       'WebLeakDetector.cpp',
       'WebLocalFrameImpl.cpp',
       'WebLocalFrameImpl.h',
       'WebMIDIPermissionRequest.cpp',
       'WebMediaDevicesRequest.cpp',
-      'WebMediaPlayerClientImpl.cpp',
-      'WebMediaPlayerClientImpl.h',
       'WebMediaStreamRegistry.cpp',
       'WebNetworkStateNotifier.cpp',
       'WebNode.cpp',
       'WebNodeList.cpp',
       'WebOptionElement.cpp',
       'WebPagePopupImpl.cpp',
       'WebPagePopupImpl.h',
       'WebPageSerializer.cpp',
       'WebPageSerializerImpl.cpp',
       'WebPageSerializerImpl.h',
@@ skipping 123 matching lines @@
         {
           'web_unittest_files': [
             # Mac uses ScrollAnimatorMac instead of ScrollAnimatorNone.
             'tests/ScrollAnimatorNoneTest.cpp',
           ],
         }
       ],
     ],
   },
 }