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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef MEDIA_BASE_CDM_PROMISE_H_
      6 #define MEDIA_BASE_CDM_PROMISE_H_
      7 
      8 #include <string>
      9 
     10 #include "base/basictypes.h"
     11 #include "base/callback.h"
     12 #include "media/base/media_export.h"
     13 #include "media/base/media_keys.h"
     14 
     15 namespace media {
     16 
     17 // Interface for promises being resolved/rejected in response to various
     18 // session actions. These may be called synchronously or asynchronously.
     19 // The promise must be resolved or rejected exactly once. It is expected that
     20 // the caller free the promise once it is resolved/rejected.
     21 //
     22 // This is only the base class, as parameter to resolve() varies.
     23 class MEDIA_EXPORT CdmPromise {
     24  public:
     25   typedef base::Callback<void(MediaKeys::Exception exception_code,
     26                               uint32 system_code,
     27                               const std::string& error_message)>
     28       PromiseRejectedCB;
     29 
     30   virtual ~CdmPromise();
     31 
     32   // Used to indicate that the operation failed. |exception_code| must be
     33   // specified. |system_code| is a Key System-specific value for the error
     34   // that occurred, or 0 if there is no associated status code or such status
     35   // codes are not supported by the Key System. |error_message| is optional.
     36   virtual void reject(MediaKeys::Exception exception_code,
     37                       uint32 system_code,
     38                       const std::string& error_message);
     39 
     40  protected:
     41   CdmPromise();
     42   CdmPromise(PromiseRejectedCB reject_cb);
     43 
     44   PromiseRejectedCB reject_cb_;
     45 
     46   // Keep track of whether the promise hasn't been resolved or rejected yet.
     47   bool is_pending_;
     48 
     49   DISALLOW_COPY_AND_ASSIGN(CdmPromise);
     50 };
     51 
     52 template <typename T>
     53 class MEDIA_EXPORT CdmPromiseTemplate : public CdmPromise {
     54  public:
     55   CdmPromiseTemplate(base::Callback<void(const T&)> resolve_cb,
     56                      PromiseRejectedCB rejected_cb);
     57   virtual ~CdmPromiseTemplate();
     58   virtual void resolve(const T& result);
     59 
     60  private:
     61   base::Callback<void(const T&)> resolve_cb_;
     62 
     63   DISALLOW_COPY_AND_ASSIGN(CdmPromiseTemplate);
     64 };
     65 
     66 // Specialization for no parameter to resolve().
     67 template <>
     68 class MEDIA_EXPORT CdmPromiseTemplate<void> : public CdmPromise {
     69  public:
     70   CdmPromiseTemplate(base::Callback<void(void)> resolve_cb,
     71                      PromiseRejectedCB rejected_cb);
     72   virtual ~CdmPromiseTemplate();
     73   virtual void resolve();
     74 
     75  protected:
     76   // Allow subclasses to completely override the implementation.
     77   CdmPromiseTemplate();
     78 
     79  private:
     80   base::Callback<void(void)> resolve_cb_;
     81 
     82   DISALLOW_COPY_AND_ASSIGN(CdmPromiseTemplate);
     83 };
     84 
     85 }  // namespace media
     86 
     87 #endif  // MEDIA_BASE_CDM_PROMISE_H_
     88