Add a bool return value to media::Decryptor::GenerateKeyRequest().

media/base/decryptor.h

 // Copyright (c) 2012 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_DECRYPTOR_H_
 #define MEDIA_BASE_DECRYPTOR_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 24 matching lines @@
   enum Status {
     kSuccess,  // Decryption successfully completed. Decrypted buffer ready.
     kNoKey,  // No key is available to decrypt.
     kError  // Key is available but an error occurred during decryption.
   };
 
   Decryptor() {}
   virtual ~Decryptor() {}
 
   // Generates a key request for the |key_system| with |init_data| provided.
-  virtual void GenerateKeyRequest(const std::string& key_system,
+  // Returns true if generating key request succeeded, false otherwise.
+  // Note: AddKey() and CancelKeyRequest() should only be called after
+  // GenerateKeyRequest() returns true.
+  virtual bool GenerateKeyRequest(const std::string& key_system,
                                   const uint8* init_data,
                                   int init_data_length) = 0;
 
   // Adds a |key| to the |key_system|. The |key| is not limited to a decryption
   // key. It can be any data that the key system accepts, such as a license.
   // If multiple calls of this function set different keys for the same
   // key ID, the older key will be replaced by the newer key.
   virtual void AddKey(const std::string& key_system,
                       const uint8* key,
                       int key_length,
@@ skipping 26 matching lines @@
   // and NULL buffer.
   virtual void Stop() = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(Decryptor);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_DECRYPTOR_H_