Add PPAPI decryptor interfaces.

ppapi/api/dev/ppp_content_decryptor_dev.idl

+/* 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.
+ */
+
+/**
+ * This file defines the <code>PPP_ContentDecryptor_Dev</code>
+ * interface.
+ */
+label Chrome {
+  M23 = 0.1
+};
+
+/**
+ * <code>PPP_ContentDecryptor_Dev</code> structure contains the function
+ * pointers the decryption plugin MUST implement to provide services needed by
+ * the media stack.
+ */
+interface PPP_ContentDecryptor_Dev {
+  /**
+   * Generates a key request. key_system specifies the key or licensing system
+   * from which to request the key when the plugin provides access to multiple
+   * systems. init_data is a data buffer containing initialization data from
+   * the media data that is required for use of the plugin's key system(s).
+   */
+  PP_Bool GenerateKeyRequest(
+      [in] PP_Instance instance,
+      [in] PP_Var key_system,  /* String. */
+      [in] PP_Var init_data);  /* ArrayBuffer. */
+
+  /**
+   * Provides a key or license to use for decrypting media data for session_id.
+   */
+  PP_Bool AddKey(
+      [in] PP_Instance instance,
+      [in] PP_Var session_id,  /* String. */
+      [in] PP_Var key);        /* ArrayBuffer. */
+
+  /**
+   * Cancels a key request for session_id.
+   */
+  PP_Bool CancelKeyRequest(
+      [in] PP_Instance instance,
+      [in] PP_Var session_id);  /* String. */
+
+  /**
+   * Decrypts the block and returns the unencrypted block. In the case of
+   * media, the block contains encoded data.
+   */
+  PP_Bool Decrypt(

[xhwang, 2012/08/01 18:55:38]

We have both sync return (PP_Bool) and async callback. I am not sure how things
are supposed to work, e.g. if this function returns false, should the callback
be fired or not? We'll need to work out these details later.

[Tom Finegan, 2012/08/02 01:12:04]

At present a return of false would mean that arguments were invalid in some way,
and that no callback would happen. Agreed that we need to work out the details.

+      [in] PP_Instance instance,
+      [in] PP_Resource encrypted_block,  /* PPB_Buffer. */
+      [in] PP_CompletionCallback callback);
+
+  /**
+   * Decrypts the block then decodes it and returns the unencrypted raw
+   * (decoded) frame.
+   */
+  PP_Bool DecryptAndDecode(
+      [in] PP_Instance instance,
+      [in] PP_Resource encrypted_block,  /* PPB_Buffer. */
+      [in] PP_CompletionCallback callback);
+};