Remove WebThemeEngine

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 1336fcad1f056b7c17b0ca2c89aaa8c894067fc5..4d43075d1c2a5ce89c518de98f346fa7d3388073 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::WebThemeEngine* PlatformImpl::themeEngine() {
-  return &theme_engine_;
-}
-
 blink::WebString PlatformImpl::defaultLocale() {
   return blink::WebString::fromUTF8("en-US");
 }