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..8b9b5e4d7e7f5ad8f1f29583e57ece523f0582c0 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