Convert CreateCdmBuffer() to use size_t for |capacity|

media/cdm/simple_cdm_buffer.h

 // Copyright 2015 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_CDM_SIMPLE_CDM_BUFFER_H_
 #define MEDIA_CDM_SIMPLE_CDM_BUFFER_H_
 
+#include <stddef.h>
 #include <stdint.h>
+
 #include <vector>
 
 #include "base/macros.h"
 #include "media/cdm/api/content_decryption_module.h"
 
 namespace media {
 
 // cdm::Buffer implementation that provides access to memory. This is a simple
 // implementation that stores the data in a std::vector<uint8_t>.
 class SimpleCdmBuffer : public cdm::Buffer {
  public:
-  static SimpleCdmBuffer* Create(uint32_t capacity);
+  static SimpleCdmBuffer* Create(size_t capacity);
 
   // cdm::Buffer implementation.
   void Destroy() final;
   uint32_t Capacity() const final;
   uint8_t* Data() final;
   void SetSize(uint32_t size) final;
   uint32_t Size() const final;
 
  private:
   SimpleCdmBuffer(uint32_t capacity);
   ~SimpleCdmBuffer() final;
 
   std::vector<uint8_t> buffer_;
   uint32_t size_;
 
   DISALLOW_COPY_AND_ASSIGN(SimpleCdmBuffer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_CDM_SIMPLE_CDM_BUFFER_H_