Verify promise type before casting.

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"
@@ skipping 17 matching lines @@
     NOT_SUPPORTED_ERROR,
     INVALID_STATE_ERROR,
     INVALID_ACCESS_ERROR,
     QUOTA_EXCEEDED_ERROR,
     UNKNOWN_ERROR,
     CLIENT_ERROR,
     OUTPUT_ERROR,
     NUM_RESULT_CODES
   };
 
+  enum ResolveParameterType {
+    VOID_TYPE,
+    STRING_TYPE,
+    KEY_IDS_VECTOR_TYPE
+  };
+
   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);
 
+  virtual ResolveParameterType GetResolveParameterType() const = 0;
+
  protected:
   CdmPromise();
   CdmPromise(PromiseRejectedCB reject_cb);
 
   // If constructed with a |uma_name| (which must be the name of a
   // CdmPromiseResult UMA), CdmPromise will report the promise result (success
   // or rejection code).
   CdmPromise(PromiseRejectedCB reject_cb, const std::string& uma_name);
 
   PromiseRejectedCB reject_cb_;
 
   // Keep track of whether the promise hasn't been resolved or rejected yet.
   bool is_pending_;
 
   // UMA to report result to.
   std::string uma_name_;
 
   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);
-  CdmPromiseTemplate(base::Callback<void(const T&)> resolve_cb,
-                     PromiseRejectedCB rejected_cb,
-                     const std::string& uma_name);
-  virtual ~CdmPromiseTemplate();
-  virtual void resolve(const T& result);
-
- protected:
-  // Allow subclasses to completely override the implementation.
-  // TODO(jrummell): Remove when derived class SessionLoadedPromise
-  // (in ppapi_decryptor.cc) is no longer needed.
-  CdmPromiseTemplate();
-
- 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);
   CdmPromiseTemplate(base::Callback<void(void)> resolve_cb,
                      PromiseRejectedCB rejected_cb,
                      const std::string& uma_name);
   virtual ~CdmPromiseTemplate();
   virtual void resolve();
+  virtual ResolveParameterType GetResolveParameterType() const OVERRIDE;
 
  protected:
   // Allow subclasses to completely override the implementation.
   CdmPromiseTemplate();
 
  private:
   base::Callback<void(void)> resolve_cb_;
 
   DISALLOW_COPY_AND_ASSIGN(CdmPromiseTemplate);
 };
+
+template <>
+class MEDIA_EXPORT CdmPromiseTemplate<std::string> : public CdmPromise {
+ public:
+  CdmPromiseTemplate(base::Callback<void(const std::string&)> resolve_cb,
+                     PromiseRejectedCB rejected_cb);
+  CdmPromiseTemplate(base::Callback<void(const std::string&)> resolve_cb,
+                     PromiseRejectedCB rejected_cb,
+                     const std::string& uma_name);
+  virtual ~CdmPromiseTemplate();
+  virtual void resolve(const std::string& result);
+  virtual ResolveParameterType GetResolveParameterType() const OVERRIDE;
+
+ protected:
+  // Allow subclasses to completely override the implementation.
+  // TODO(jrummell): Remove when derived class SessionLoadedPromise
+  // (in ppapi_decryptor.cc) is no longer needed.
+  CdmPromiseTemplate();
+
+ private:
+  base::Callback<void(const std::string&)> resolve_cb_;
+
+  DISALLOW_COPY_AND_ASSIGN(CdmPromiseTemplate);
+};
+
+template <>
+class MEDIA_EXPORT CdmPromiseTemplate<KeyIdsVector> : public CdmPromise {
+ public:
+  CdmPromiseTemplate(base::Callback<void(const KeyIdsVector&)> resolve_cb,
+                     PromiseRejectedCB rejected_cb);
+  CdmPromiseTemplate(base::Callback<void(const KeyIdsVector&)> resolve_cb,
+                     PromiseRejectedCB rejected_cb,
+                     const std::string& uma_name);
+  virtual ~CdmPromiseTemplate();
+  virtual void resolve(const KeyIdsVector& result);
+  virtual ResolveParameterType GetResolveParameterType() const OVERRIDE;
+
+ private:
+  base::Callback<void(const KeyIdsVector&)> resolve_cb_;
+
+  DISALLOW_COPY_AND_ASSIGN(CdmPromiseTemplate);
+};
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_CDM_PROMISE_H_