Use enum hack to define kInvalidCdmId.

media/base/cdm_context.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BASE_CDM_CONTEXT_H_
 #define MEDIA_BASE_CDM_CONTEXT_H_
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "media/base/media_export.h"
 
 namespace media {
 
 class Decryptor;
 
 // An interface representing the context that a media player needs from a
 // content decryption module (CDM) to decrypt (and decode) encrypted buffers.
 // This is used to pass the CDM to the media player (e.g. SetCdm()).
 class MEDIA_EXPORT CdmContext {
  public:
   // Indicates an invalid CDM ID. See GetCdmId() for details.
-  static const int kInvalidCdmId;
+  enum { kInvalidCdmId = 0 };
 
   virtual ~CdmContext();
 
   // Gets the Decryptor object associated with the CDM. Returns nullptr if the
   // CDM does not support a Decryptor (i.e. platform-based CDMs where decryption
   // occurs implicitly along with decoding). The returned object is only
   // guaranteed to be valid during the CDM's lifetime.
   virtual Decryptor* GetDecryptor() = 0;
 
   // Returns an ID that can be used to find a remote CDM, in which case this CDM
@@ skipping 15 matching lines @@
 // Callback to notify that the CdmContext has been completely attached to
 // the media pipeline. Parameter indicates whether the operation succeeded.
 typedef base::Callback<void(bool)> CdmAttachedCB;
 
 // A dummy implementation of CdmAttachedCB.
 MEDIA_EXPORT void IgnoreCdmAttached(bool success);
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_CDM_CONTEXT_H_