Remove unused WebMIMERegistry

sky/viewer/platform/platform_impl.cc

Index: sky/viewer/platform/platform_impl.cc
diff --git a/sky/viewer/platform/platform_impl.cc b/sky/viewer/platform/platform_impl.cc
index b91316778129b43fe42591877f986a24696ec069..1336fcad1f056b7c17b0ca2c89aaa8c894067fc5 100644
--- a/sky/viewer/platform/platform_impl.cc
+++ b/sky/viewer/platform/platform_impl.cc
@@ -58,10 +58,6 @@ PlatformImpl::PlatformImpl(mojo::ApplicationImpl* app)
 PlatformImpl::~PlatformImpl() {
 }
 
-blink::WebMimeRegistry* PlatformImpl::mimeRegistry() {
-  return &mime_registry_;
-}
-
 blink::WebThemeEngine* PlatformImpl::themeEngine() {
   return &theme_engine_;
 }