Fix media_mojo builds

media/base/cdm_promise.h

Index: media/base/cdm_promise.h
diff --git a/media/base/cdm_promise.h b/media/base/cdm_promise.h
index d48a11408c8c91fed66a902c45626ecd87d07c2a..0f9a920f8885cd4e2c990736abf6aa6eb49248df 100644
--- a/media/base/cdm_promise.h
+++ b/media/base/cdm_promise.h
@@ -72,24 +72,22 @@ class MEDIA_EXPORT CdmPromise {
   DISALLOW_COPY_AND_ASSIGN(CdmPromise);
 };
 
-// For some reason the Windows compiler is not happy with the implementation
-// of CdmPromiseTemplate being in the .cc file, so moving it here.
 template <typename... T>
 struct CdmPromiseTraits {};
 
 template <>
-struct CdmPromiseTraits<> {
-  static const CdmPromise::ResolveParameterType kType = CdmPromise::VOID_TYPE;
+struct MEDIA_EXPORT CdmPromiseTraits<> {
+  static const CdmPromise::ResolveParameterType kType;
 };
 
 template <>
-struct CdmPromiseTraits<int> {
-  static const CdmPromise::ResolveParameterType kType = CdmPromise::INT_TYPE;
+struct MEDIA_EXPORT CdmPromiseTraits<int> {
+  static const CdmPromise::ResolveParameterType kType;
 };
 
 template <>
-struct CdmPromiseTraits<std::string> {
-  static const CdmPromise::ResolveParameterType kType = CdmPromise::STRING_TYPE;
+struct MEDIA_EXPORT CdmPromiseTraits<std::string> {
+  static const CdmPromise::ResolveParameterType kType;
 };
 
 // This class adds the resolve(T) method. This class is still an interface, and