Add Promises for EME (Chromium side)

media/base/cdm_promise.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_PROMISE_H_
+#define MEDIA_BASE_CDM_PROMISE_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "media/base/media_export.h"
+#include "media/base/media_keys.h"
+
+namespace media {
+
+// Interface for promises being resolved/rejected in response to various
+// session actions. These may be called synchronously or asynchronously.
+// The promise must be resolved or rejected exactly once. It is expected that
+// the caller free the promise once it is resolved/rejected.
+//
+// This is only the base class, as parameter to resolve() varies.
+class MEDIA_EXPORT CdmPromise {
+ public:
+  typedef base::Callback<void(MediaKeys::Exception exception_code,
+                              uint32 system_code,
+                              const std::string& error_message)>
+      PromiseRejectedCB;
+
+  virtual ~CdmPromise();
+
+  // Used to indicate that the operation failed. |exception_code| must be
+  // specified. |system_code| is a Key System-specific value for the error
+  // that occurred, or 0 if there is no associated status code or such status
+  // codes are not supported by the Key System. |error_message| is optional.
+  virtual void reject(MediaKeys::Exception exception_code,
+                      uint32 system_code,
+                      const std::string& error_message);
+
+ protected:
+  CdmPromise();
+  CdmPromise(PromiseRejectedCB reject_cb);
+
+  PromiseRejectedCB reject_cb_;
+
+  // Keep track of whether the promise hasn't been resolved or rejected yet.
+  bool is_pending_;
+
+  DISALLOW_COPY_AND_ASSIGN(CdmPromise);
+};
+
+template <typename T>
+class MEDIA_EXPORT CdmPromiseTemplate : public CdmPromise {
+ public:
+  CdmPromiseTemplate(base::Callback<void(const T&)> resolve_cb,
+                     PromiseRejectedCB rejected_cb);
+  virtual ~CdmPromiseTemplate();
+  virtual void resolve(const T& result);
+
+ private:
+  base::Callback<void(const T&)> resolve_cb_;
+
+  DISALLOW_COPY_AND_ASSIGN(CdmPromiseTemplate);
+};
+
+// Specialization for no parameter to resolve().
+template <>
+class MEDIA_EXPORT CdmPromiseTemplate<void> : public CdmPromise {
+ public:
+  CdmPromiseTemplate(base::Callback<void(void)> resolve_cb,
+                     PromiseRejectedCB rejected_cb);
+  virtual ~CdmPromiseTemplate();
+  virtual void resolve();
+
+ protected:
+  // Allow subclasses to completely override the implementation.
+  CdmPromiseTemplate();
+
+ private:
+  base::Callback<void(void)> resolve_cb_;
+
+  DISALLOW_COPY_AND_ASSIGN(CdmPromiseTemplate);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_CDM_PROMISE_H_