Move MediaStreamSource to platform/

Source/core/core.gypi

 {
     'variables': {
         'core_idl_files': [
             'css/CSS.idl',
             'css/CSSCharsetRule.idl',
             'css/CSSFontFaceLoadEvent.idl',
             'css/CSSFontFaceRule.idl',
             'css/CSSHostRule.idl',
             'css/CSSImportRule.idl',
             'css/CSSKeyframeRule.idl',
@@ skipping 2945 matching lines @@
             'platform/mac/ScrollElasticityController.mm',
             'platform/mac/ThemeMac.h',
             'platform/mac/ThemeMac.mm',
             'platform/mac/WebFontCache.mm',
             'platform/mediastream/MediaStreamCenter.cpp',
             'platform/mediastream/MediaStreamCenter.h',
             'platform/mediastream/MediaStreamComponent.cpp',
             'platform/mediastream/MediaStreamComponent.h',
             'platform/mediastream/MediaStreamDescriptor.cpp',
             'platform/mediastream/MediaStreamDescriptor.h',
-            'platform/mediastream/MediaStreamSource.cpp',
-            'platform/mediastream/MediaStreamSource.h',
             'platform/mediastream/RTCDTMFSenderHandler.cpp',
             'platform/mediastream/RTCDTMFSenderHandler.h',
             'platform/mediastream/RTCDTMFSenderHandlerClient.h',
             'platform/mediastream/RTCDataChannelHandler.cpp',
             'platform/mediastream/RTCDataChannelHandler.h',
             'platform/mediastream/RTCDataChannelHandlerClient.h',
             'platform/mediastream/RTCPeerConnectionHandler.cpp',
             'platform/mediastream/RTCPeerConnectionHandler.h',
             'platform/mediastream/RTCPeerConnectionHandlerClient.h',
             'platform/mediastream/RTCSessionDescriptionRequest.h',
@@ skipping 492 matching lines @@
             'testing/TypeConversions.h',
             '<(SHARED_INTERMEDIATE_DIR)/blink/InternalSettingsGenerated.cpp',
             '<(SHARED_INTERMEDIATE_DIR)/blink/InternalSettingsGenerated.h',
         ],
         'webcore_platform_support_files': [
             'platform/chromium/support/WebArrayBuffer.cpp',
             'platform/chromium/support/WebCrypto.cpp',
             'platform/chromium/support/WebCursorInfo.cpp',
             'platform/chromium/support/WebMediaConstraints.cpp',
             'platform/chromium/support/WebMediaStream.cpp',
-            'platform/chromium/support/WebMediaStreamSource.cpp',
             'platform/chromium/support/WebMediaStreamTrack.cpp',
             'platform/chromium/support/WebRTCSessionDescription.cpp',
             'platform/chromium/support/WebRTCSessionDescriptionRequest.cpp',
             'platform/chromium/support/WebRTCStatsRequest.cpp',
             'platform/chromium/support/WebRTCStatsResponse.cpp',
             'platform/chromium/support/WebRTCVoidRequest.cpp',
             'platform/chromium/support/WebScrollbarImpl.cpp',
             'platform/chromium/support/WebScrollbarImpl.h',
             'platform/chromium/support/WebScrollbarThemeClientImpl.cpp',
             'platform/chromium/support/WebScrollbarThemeClientImpl.h',
@@ skipping 47 matching lines @@
             'platform/graphics/gpu/DrawingBufferTest.cpp',
             'platform/image-decoders/ImageDecoderTest.cpp',
             'platform/image-decoders/gif/GIFImageDecoderTest.cpp',
             'platform/image-decoders/jpeg/JPEGImageDecoderTest.cpp',
             'platform/image-decoders/webp/WEBPImageDecoderTest.cpp',
             'platform/testing/FakeWebGraphicsContext3D.h',
             'rendering/RenderOverflowTest.cpp',
         ],
     }
 }