media: Make MediaKeys ref-counted.

media/base/cdm_initialized_promise.h

Index: media/base/cdm_initialized_promise.h
diff --git a/media/base/cdm_initialized_promise.h b/media/base/cdm_initialized_promise.h
index bc4a56970ce0db4917c6d8abec770e55f836719d..3a6ff1147b5f35f848cf01d645b345305f576d75 100644
--- a/media/base/cdm_initialized_promise.h
+++ b/media/base/cdm_initialized_promise.h
@@ -19,7 +19,7 @@ namespace media {
 class MEDIA_EXPORT CdmInitializedPromise : public SimpleCdmPromise {
  public:
   CdmInitializedPromise(const CdmCreatedCB& cdm_created_cb,
-                        scoped_ptr<MediaKeys> cdm);
+                        const scoped_refptr<MediaKeys>& cdm);
   ~CdmInitializedPromise() override;
 
   // SimpleCdmPromise implementation.
@@ -30,7 +30,9 @@ class MEDIA_EXPORT CdmInitializedPromise : public SimpleCdmPromise {
 
  private:
   CdmCreatedCB cdm_created_cb_;
-  scoped_ptr<MediaKeys> cdm_;
+
+  // Holds a ref-count of the CDM.
+  scoped_refptr<MediaKeys> cdm_;
 };
 
 }  // namespace media