Add decoder de-initialize and reset to the Pepper CDM API.

ppapi/api/private/ppp_content_decryptor_private.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_Private</code>
  * interface. Note: This is a special interface, only to be used for Content
  * Decryption Modules, not normal plugins.
  */
 label Chrome {
-  M23 = 0.2
+  M24 = 0.3
 };
 
 /**
  * <code>PPP_ContentDecryptor_Private</code> structure contains the function
  * pointers the decryption plugin must implement to provide services needed by
  * the browser. This interface provides the plugin side support for the Content
  * Decryption Module (CDM) for v0.1 of the proposed Encrypted Media Extensions:
  * http://goo.gl/rbdnR
  */
 interface PPP_ContentDecryptor_Private {
@@ skipping 70 matching lines @@
    * @param[in] encrypted_block_info A <code>PP_EncryptedBlockInfo</code> that
    * contains all auxiliary information needed for decryption of the
    * <code>encrypted_block</code>.
    */
   void Decrypt(
       [in] PP_Instance instance,
       [in] PP_Resource encrypted_block,
       [in] PP_EncryptedBlockInfo encrypted_block_info);
 
   /**
+   * Resets the video decoder. Reset completion is reported to the browser
+   * using the <code>DecoderReset()</code> method on the
+   * <code>PPB_ContentDecryptor_Private</code> interface.
+   *
+   * @param[in] request_id A request ID that allows the browser to associate a
+   * request to reset the video decoder with the corresponding call to the
+   * <code>DecoderReset()</code> method on the

[xhwang, 2012/10/09 16:27:27]

It looks like the PPB interfaces are sharing APIs between video and audio, e.g.
DecoderReset is used for both video and audio. Why don't also have common APIs
for video/audio in PPP calls? If we do that, we can have something like:
void ResetDecoder(instance, stream_type, request_id), where the stream_type can
be enum/int/bool so that we can differentiate b/w video and auido.

Actually we can also do this for DecryptAndDecodeFrame. If we do that this
function should be renamed to DecryptAndDecode. Also, since we've moved video
initialization out of DecryptAndDecodeFrame, is there any reason that
DecryptAndDecodeFrame takes PP_EncryptedVideoFrameInfo instead of just
PP_EncryptedBlockInfo?

[Tom Finegan, 2012/10/10 00:39:32]

+ddorwin,fischman:
We still need audio and video specific delivery methods on the PPB side, but
generalizing DecryptAndDecode, ResetDecoder, and StopDecoder seems like a good
idea with the exception being Ami's noting that if we have an InitializeDecoder
we should have a DeinitializeDecoder (instead of StopDecoder).
No, I think we can get rid of PP_EncryptedVideoFrameInfo and do what you've
suggested. 

TODOs:

1) Add PP_DecryptedStreamType to pepper and DecryptedStreamType to CDM.h 
(I am not attached to these names; made them up just now for discussion)
2) Replace cdm::StopVideoDecoder with DeinitializeDecoder
3) As mentioned above, generalize the PPP decode methods (remove the words frame
and video, remove the type PP_EncryptedVideoFrameInfo).
4) Generalize the CDM.h decode methods.

I think 1 and 2 make sense as part of this CL, and 3 and 4 should be another CL.
What does everyone else think?

+   * <code>PPB_ContentDecryptor_Private</code> interface.
+   */
+  void ResetVideoDecoder(
+      [in] PP_Instance instance,
+      [in] uint32_t request_id);
+
+  /**
+   * Stops the video decoder. Stop completion is reported to the browser using
+   * the <code>DecoderStopped()</code> method on the
+   * <code>PPB_ContentDecryptor_Private</code> interface.
+   *
+   * @param[in] request_id A request ID that allows the browser to associate a
+   * request to stop the video decoder with the corresponding call to the
+   * <code>DecoderStopped()</code> method on the
+   * <code>PPB_ContentDecryptor_Private</code> interface.
+   */
+  void StopVideoDecoder(

[Ami GONE FROM CHROMIUM, 2012/10/09 07:25:54]

Is there a reason this is "Stop" and not "Destroy" other than consistency with
the poor naming in media/ ?

[xhwang, 2012/10/09 16:27:27]

In the CDM world, a video decoder can be reinitialized after it's stopped. This
is the plan for handling config change in media source (not implemented yet
though). In this sense, "stop" sounds better then "destroy".

[Ami GONE FROM CHROMIUM, 2012/10/09 16:41:05]

Then how about DeinitializeVideoDecoder()?

Stop implies Start...

[Tom Finegan, 2012/10/10 00:39:32]

Agreed, discussing this in the above comment.

+      [in] PP_Instance instance,
+      [in] uint32_t request_id);
+
+  /**
    * Decrypts encrypted_video_frame, decodes it, and returns the unencrypted 
    * uncompressed (decoded) video frame to the browser via the
    * <code>DeliverFrame()</code> method on the
    * <code>PPB_ContentDecryptor_Private</code> interface.
    *
    * @param[in] encrypted_video_frame A <code>PP_Resource</code> corresponding
    * to a <code>PPB_Buffer_Dev</code> resource that contains an encrypted video
    * frame.
    *
    * @param[in] encrypted_video_frame_info A 
    * <code>PP_EncryptedVideoFrameInfo</code> that contains all information
    * needed to decrypt and decode <code>encrypted_video_frame</code>.
    */
   void DecryptAndDecodeFrame(
       [in] PP_Instance instance,
       [in] PP_Resource encrypted_video_frame,
       [in] PP_EncryptedVideoFrameInfo encrypted_video_frame_info);
 };