Add ContentDecryptionModule interface.

webkit/media/crypto/content_decryption_module.h

Index: webkit/media/crypto/content_decryption_module.h
diff --git a/webkit/media/crypto/content_decryption_module.h b/webkit/media/crypto/content_decryption_module.h
new file mode 100644
index 0000000000000000000000000000000000000000..099cd55c7982ca658b27ea0c1ee0d009bc03c039
--- /dev/null
+++ b/webkit/media/crypto/content_decryption_module.h
@@ -0,0 +1,123 @@
+// 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 WEBKIT_MEDIA_CRYPTO_CONTENT_DECRYPTION_MODULE_H_
+#define WEBKIT_MEDIA_CRYPTO_CONTENT_DECRYPTION_MODULE_H_
+
+#if defined(_MSC_VER)
+typedef unsigned char uint8_t;
+typedef __int64 int64_t;
+#else
+#include <stdint.h>
+#endif
+
+class ContentDecryptionModule;
+
+extern ContentDecryptionModule* CdmCreateInstance();
+extern const char* CdmGetVersion();
+
+enum CdmStatus {
+  kCdmStatusSuccess = 0,
+  kCdmStatusErrorUnknown,
+  kCdmStatusErrorNoKey
+};
+
+// An input buffer can be split into several continuous subsamples.
+// A SubsampleEntry specifies the number of clear and cypher bytes in each
+// subsample. For example, the following buffer has three subsamples:
+//
+// |<----- subsample1 ----->|<----- subsample2 ----->|<----- subsample3 ----->|
+// |    clear1    | cypher1 |  clear2  |   cypher2   | clear3 |    cypher3    |
+//
+// For decryption, all of the cypher bytes in a buffer should be concatenated
+// (in the subsample order) into a single logical stream. The clear bytes should
+// not be considered as part of decryption.
+//
+// Stream to decrypt:   | cypher1 |   cypher2   |    cypher3    |
+// Decrypted stream:    |decryped1|  decryped2  |   decryped3   |
+//
+// After decryption, the decrypted bytes should be copied over the position
+// of the corresponding cypher bytes in the original buffer to form the output
+// buffer. Following the above example, the decrypted buffer should be:
+//
+// |<----- subsample1 ----->|<----- subsample2 ----->|<----- subsample3 ----->|
+// |    clear1    |decryped1|  clear2  |  decryped2  | clear3 |   decryped3   |
+//
+struct SubsampleEntry {
+  int clear_bytes;
+  int cypher_bytes;
+};
+
+struct InputBuffer {
+  uint8_t* data;  // Pointer to the beginning of the input data.
+  int data_size;  // Size (in bytes) of |data|.
+  int data_offset;  // Number of bytes to be discarded before decryption.
+  uint8_t* key_id;  // Key ID to identify the decryption key.
+  int key_id_size;  // Size (in bytes) of |key_id|.
+  uint8_t* iv;  // Initialization vector.
+  int iv_size;  // Size (in bytes) of |iv|.
+  uint8_t* checksum;
+  int checksum_size;  // Size (in bytes) of the |checksum|.
+  struct SubsampleEntry* subsamples;
+  int num_subsamples;  // Number of subsamples in |subsamples|.
+  int64_t timestamp;  // Presentation timestamp in milliseconds.
+  int64_t duration;  // Duration in milliseconds.
+};
+
+struct OutputBuffer {
+  uint8_t* data;  // Pointer to the beginning of the output data.
+  int data_size;  // Size (in bytes) of |data|.
+  int64_t timestamp;  // Presentation timestamp in milliseconds.
+  int64_t duration;  // Duration in milliseconds.
+};
+
+class ContentDecryptionModule {
+ public:
+  // Generates a |key_request| as well as a |session_id| given the |init_data|.
+  // The CDM may also generate a |default_url|.

[ddorwin, 2012/08/15 02:14:57]

s/generate/extract/

[xhwang, 2012/08/15 04:27:46]

Done.

+  // Returns kCdmStatusSuccess if the key request is successfully generated,
+  // in which case the callee should allocates memory for the output parameters

[ddorwin, 2012/08/15 02:14:57]

s/should/should have/.
After the return, that happened in the past.

[xhwang, 2012/08/15 04:27:46]

Done.

+  // (e.g session_id) and takes ownership of them.

[ddorwin, 2012/08/15 02:14:57]

But isn't ownership passed to the caller on return?

[xhwang, 2012/08/15 04:27:46]

Done.

+  // Returns kCdmStatusErrorUnknown otherwise, in which case the output
+  // parameters should not be used by the caller.
+  virtual CdmStatus GenerateKeyRequest(const uint8_t* init_data,
+                                       int init_data_size,
+                                       char** session_id,
+                                       int* session_id_size,
+                                       uint8_t** key_request,
+                                       int* key_request_size,
+                                       char** default_url,
+                                       int* default_url_size) = 0;
+
+  // Adds the |key| to the CDM.
+  // Returns kCdmStatusSuccess if the key is successfully added.
+  // Returns kCdmStatusErrorUnknown otherwise.
+  virtual CdmStatus AddKey(const char* session_id,
+                           int session_id_size,
+                           const uint8_t* key,
+                           int key_size) = 0;
+
+  // Cancels any pending key request made to the CDM for |session_id|.
+  // Returns kCdmStatusSuccess if there is no key request to be canceled or

[ddorwin, 2012/08/15 02:14:57]

I would swap the phrases around "or" since the latter seems more common.

[xhwang, 2012/08/15 04:27:46]

Done.

+  // all pending key requests for |session_id| are successfully canceled.
+  // Returns kCdmStatusErrorUnknown otherwise.
+  virtual CdmStatus CancelKeyRequest(const char* session_id,
+                                     int session_id_size) = 0;
+
+  // Decrypts the |encrypted_buffer|.
+  // Returns kCdmStatusSuccess if decryption succeeds, in which case the callee
+  // should fill the |decrypted_buffer| and take ownership of |data| in

[ddorwin, 2012/08/15 02:14:57]

Similar to above.

[xhwang, 2012/08/15 04:27:46]

Done.

+  // |decrypted_buffer|.
+  // Returns kCdmStatusErrorNoKey if the CDM does not have a key to decrypt.

[ddorwin, 2012/08/15 02:14:57]

... have the necessary decryption key.

[xhwang, 2012/08/15 04:27:46]

Done.

+  // Returns kCdmStatusErrorUnknown if any other error happens.
+  // In these two cases, |decrypted_buffer| should not be used by the caller.
+  virtual CdmStatus Decrypt(const char* session_id,
+                            int session_id_size,
+                            const InputBuffer& encrypted_buffer,
+                            OutputBuffer* decrypted_buffer) = 0;
+
+  virtual ~ContentDecryptionModule() {};
+};
+
+#endif  // WEBKIT_MEDIA_CRYPTO_CONTENT_DECRYPTION_MODULE_H_