I'm seeing the following build error:

In file included from gen/third_party/WebKit/Source/platform/platform_jumbo_34.cc:9:
In file included from ../../third_party/ffmpeg/../../third_party/WebKit/Source/platform/fonts/WebFontTypefaceFactory.cpp:5:
../../third_party/WebKit/Source/platform/fonts/WebFontTypefaceFactory.h:18:7: error: redefinition of 'WebFontTypefaceFactory'
class WebFontTypefaceFactory {
      ^
../../third_party/ffmpeg/../../third_party/WebKit/Source/platform/fonts/WebFontDecoder.cpp:37:10: note: '../../third_party/WebKit/Source/platform/fonts/WebFontTypefaceFactory.h' included multiple times, additional include site here
#include "platform/fonts/WebFontTypefaceFactory.h"
         ^
../../third_party/ffmpeg/../../third_party/WebKit/Source/platform/fonts/WebFontTypefaceFactory.cpp:5:10: note: '../../third_party/WebKit/Source/platform/fonts/WebFontTypefaceFactory.h' included multiple times, additional include site here
#include "platform/fonts/WebFontTypefaceFactory.h"
         ^
../../third_party/WebKit/Source/platform/fonts/WebFontTypefaceFactory.h:18:7: note: unguarded header; consider using #ifdef guards or #pragma once
class WebFontTypefaceFactory {
      ^
1 error generated.