Fix linker warning in broadcast_channel.mojom-blink.obj.

third_party/WebKit/Source/build/scripts/templates/RuntimeEnabledFeatures.h.tmpl

 {% from 'macros.tmpl' import license %}
 {{license()}}
 
 #ifndef RuntimeEnabledFeatures_h
 #define RuntimeEnabledFeatures_h
 
 #include <string>
 
-#include "platform/PlatformExport.h"
+#include "platform/RuntimeEnabledFeaturesExport.h"
 #include "wtf/Allocator.h"
 #include "wtf/Forward.h"
 #include "wtf/build_config.h"
 
 namespace blink {
 
 // A class that stores static enablers for all experimental features.
 
-class PLATFORM_EXPORT RuntimeEnabledFeatures {
+class RUNTIME_ENABLED_FEATURES_EXPORT RuntimeEnabledFeatures {
     STATIC_ONLY(RuntimeEnabledFeatures);
 public:
-    class PLATFORM_EXPORT Backup {
+    class RUNTIME_ENABLED_FEATURES_EXPORT Backup {
     public:
         explicit Backup();
         void restore();
 
     private:
         {% for feature in standard_features %}
         bool m_{{feature.first_lowered_name}};
         {% endfor %}
     };
 
@@ skipping 24 matching lines @@
 
 private:
     {% for feature in standard_features %}
     static bool is{{feature.name}}Enabled;
     {% endfor %}
 };
 
 } // namespace blink
 
 #endif // RuntimeEnabledFeatures_h