Keep reference to CDM to avoid it's premature destruction

media/blink/webcontentdecryptionmodule_impl.h

Index: media/blink/webcontentdecryptionmodule_impl.h
diff --git a/media/blink/webcontentdecryptionmodule_impl.h b/media/blink/webcontentdecryptionmodule_impl.h
index 989b4a08cbeee174e81460227a4a5a09f731b6fc..5425e95d8b1061ec1624ead05b9c51bbab1c93d6 100644
--- a/media/blink/webcontentdecryptionmodule_impl.h
+++ b/media/blink/webcontentdecryptionmodule_impl.h
@@ -27,9 +27,9 @@ class WebSecurityOrigin;
 namespace media {
 
 struct CdmConfig;
-class CdmContext;
 class CdmFactory;
 class CdmSessionAdapter;
+class MediaKeys;
 class WebContentDecryptionModuleSessionImpl;
 
 class MEDIA_BLINK_EXPORT WebContentDecryptionModuleImpl
@@ -52,10 +52,8 @@ class MEDIA_BLINK_EXPORT WebContentDecryptionModuleImpl
       size_t server_certificate_length,
       blink::WebContentDecryptionModuleResult result) override;
 
-  // Returns the CdmContext associated with this CDM, which must not be nullptr.
-  // TODO(jrummell): Figure out lifetimes, as WMPI may still use the decryptor
-  // after WebContentDecryptionModule is freed. http://crbug.com/330324
-  CdmContext* GetCdmContext();
+  // Returns a reference to the CDM used by |adapter_|.
+  scoped_refptr<MediaKeys> GetCdm();
 
  private:
   friend CdmSessionAdapter;