Update PPB_VideoDecoder documentation.

ppapi/cpp/video_decoder.h

Index: ppapi/cpp/video_decoder.h
diff --git a/ppapi/cpp/video_decoder.h b/ppapi/cpp/video_decoder.h
index f1f2d91fe4aff3c8b74695870048e8bb61560193..d1eded3059c1d17f645e1b9f06cc6ba67f6cd812 100644
--- a/ppapi/cpp/video_decoder.h
+++ b/ppapi/cpp/video_decoder.h
@@ -81,9 +81,8 @@ class VideoDecoder : public Resource {
                      const CompletionCallback& callback);
 
   /// Decodes a bitstream buffer. Copies |size| bytes of data from the plugin's
-  /// |buffer|. The plugin should maintain the buffer and not call Decode()
-  /// again until the decoder signals completion by returning PP_OK or by
-  /// running |callback|.
+  /// |buffer|. The plugin should wait until the decoder signals completion by
+  /// returning PP_OK or by running |callback| before calling Decode() again.
   ///
   /// In general, each bitstream buffer should contain a demuxed bitstream frame
   /// for the selected video codec. For example, H264 decoders expect to receive
@@ -105,6 +104,11 @@ class VideoDecoder : public Resource {
   /// completion.
   ///
   /// @return An int32_t containing an error code from <code>pp_errors.h</code>.
+  /// Returns PP_ERROR_FAILED if the decoder isn't initialized or if a Flush()
+  /// or Reset() call is pending.
+  /// Returns PP_ERROR_INPROGRESS if there is another Decode() call pending.
+  /// Returns PP_ERROR_NOMEMORY if a bitstream buffer can't be created.
+  /// Returns PP_ERROR_ABORTED when Reset() is called while Decode() is pending.
   int32_t Decode(uint32_t decode_id,
                  uint32_t size,
                  const void* buffer,
@@ -122,7 +126,9 @@ class VideoDecoder : public Resource {
   /// called on completion, and on success, to hold the picture descriptor.
   ///
   /// @return An int32_t containing an error code from <code>pp_errors.h</code>.
-  /// Returns PP_OK if a picture is available.
+  /// Returns PP_ERROR_FAILED if the decoder isn't initialized or if a Reset()
+  /// call is pending.
+  /// Returns PP_ERROR_INPROGRESS if there is another GetPicture() call pending.
   /// Returns PP_ERROR_ABORTED when Reset() is called, or if a call to Flush()
   /// completes while GetPicture() is pending.
   int32_t GetPicture(
@@ -136,31 +142,37 @@ class VideoDecoder : public Resource {
   /// decoder.
   void RecyclePicture(const PP_VideoPicture& picture);
 
-  /// Flushes the decoder. The plugin should call this when it reaches the end
-  /// of its video stream in order to stop cleanly. The decoder will run all
-  /// pending calls to completion. The plugin should make no further calls to
-  /// the decoder other than GetPicture() and RecyclePicture() until the decoder
-  /// signals completion by running the callback. Just before completion, any
-  /// pending GetPicture() call will complete by running the callback with
-  /// result PP_ERROR_ABORTED to signal that no more pictures are available.
+  /// Flushes the decoder. The plugin should call Flush() when it reaches the
+  /// end of its video stream in order to stop cleanly. The decoder will run any
+  /// pending Decode() call to completion. The plugin should make no further
+  /// calls to the decoder other than GetPicture() and RecyclePicture() until
+  /// the decoder signals completion by running |callback|. Just before
+  /// completion, any pending GetPicture() call will complete by running its
+  /// callback with result PP_ERROR_ABORTED to signal that no more pictures are
+  /// available. The plugin should recycle any pictures it is using before
+  /// resuming decoding.
   ///
   /// @param[in] callback A <code>CompletionCallback</code> to be called on
   /// completion.
   ///
   /// @return An int32_t containing an error code from <code>pp_errors.h</code>.
+  /// Returns PP_ERROR_FAILED if the decoder isn't initialized.
   int32_t Flush(const CompletionCallback& callback);
 
   /// Resets the decoder as quickly as possible. The plugin can call Reset() to
-  /// skip to another position in the video stream. Pending calls to Decode()
-  /// and GetPicture()) are immediately aborted, causing their callbacks to run
-  /// with PP_ERROR_ABORTED. The plugin should not make any further calls to the
-  /// decoder until the decoder signals completion by running |callback|.
+  /// skip to another position in the video stream. After Reset() returns, any
+  /// pending calls to Decode() and GetPicture()) abort, causing their callbacks
+  /// to run with PP_ERROR_ABORTED. The plugin should not make further calls to
+  /// the decoder until the decoder signals completion by running |callback|.
+  /// The pictures in use by the plugin remain valid until decoding is resumed,
+  /// but need not be recycled.
   ///
   /// @param[in] callback A <code>CompletionCallback</code> to be called on
   /// completion.
   ///
   /// @return An int32_t containing an error code from <code>pp_errors.h</code>.
-  int32_t Reset(const CompletionCallback& callback);
+    /// Returns PP_ERROR_FAILED if the decoder isn't initialized.
+int32_t Reset(const CompletionCallback& callback);
 };
 
 }  // namespace pp