Remove reference counting from media::VideoDecoder and friends.

media/filters/decrypting_video_decoder.cc

 // 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.
 
 #include "media/filters/decrypting_video_decoder.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/debug/trace_event.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/message_loop_proxy.h"
 #include "media/base/bind_to_loop.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/decryptor.h"
 #include "media/base/demuxer_stream.h"
 #include "media/base/pipeline.h"
 #include "media/base/video_decoder_config.h"
 #include "media/base/video_frame.h"
 
 namespace media {
 
 DecryptingVideoDecoder::DecryptingVideoDecoder(
     const scoped_refptr<base::MessageLoopProxy>& message_loop,
     const SetDecryptorReadyCB& set_decryptor_ready_cb)
     : message_loop_(message_loop),
+      weak_factory_(this),
       state_(kUninitialized),
       set_decryptor_ready_cb_(set_decryptor_ready_cb),
       decryptor_(NULL),
       key_added_while_decode_pending_(false),
       trace_id_(0) {
 }
 
 void DecryptingVideoDecoder::Initialize(
     const scoped_refptr<DemuxerStream>& stream,
     const PipelineStatusCB& status_cb,
     const StatisticsCB& statistics_cb) {
   DVLOG(2) << "Initialize()";
   DCHECK(message_loop_->BelongsToCurrentThread());
   DCHECK_EQ(state_, kUninitialized) << state_;
   DCHECK(stream);
   init_cb_ = BindToCurrentLoop(status_cb);
+  weak_this_ = weak_factory_.GetWeakPtr();

[Ami GONE FROM CHROMIUM, 2013/03/22 23:48:01]

Nothing ever invalidates the underlying WeakReference.
You should call weak_factory_.InvalidateWeakPtrs() in the dtor of each class in
this CL that uses this idiom.

[xhwang, 2013/03/22 23:59:03]

Hmm, is this required for all classes that uses WeakPtrFactory? Looks like
WeakPtrFactory owns internal::WeakReferenceOwner, whose dtor calls Invalidate
automatically.

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/base/memory/weak_p...

[2]
https://code.google.com/p/chromium/codesearch#chromium/src/base/memory/weak_p...

[Ami GONE FROM CHROMIUM, 2013/03/23 00:02:01]

Oh good, I think you're right!
(this is how I _thought_ it worked, but then when I looked today I missed this,
visually replacing WeakReferenceOwner with WeakReference).

 
   const VideoDecoderConfig& config = stream->video_decoder_config();
   if (!config.IsValidConfig()) {
     DLOG(ERROR) << "Invalid video stream config: "
                 << config.AsHumanReadableString();
     base::ResetAndReturn(&init_cb_).Run(PIPELINE_ERROR_DECODE);
     return;
   }
 
   // DecryptingVideoDecoder only accepts potentially encrypted stream.
   if (!config.is_encrypted()) {
     base::ResetAndReturn(&init_cb_).Run(DECODER_ERROR_NOT_SUPPORTED);
     return;
   }
 
   DCHECK(!demuxer_stream_);
   demuxer_stream_ = stream;
   statistics_cb_ = statistics_cb;
 
   state_ = kDecryptorRequested;
   set_decryptor_ready_cb_.Run(BindToCurrentLoop(base::Bind(
-      &DecryptingVideoDecoder::SetDecryptor, this)));
+      &DecryptingVideoDecoder::SetDecryptor, weak_this_)));
 }
 
 void DecryptingVideoDecoder::Read(const ReadCB& read_cb) {
   DVLOG(3) << "Read()";
   DCHECK(message_loop_->BelongsToCurrentThread());
   DCHECK(state_ == kIdle || state_ == kDecodeFinished) << state_;
   DCHECK(!read_cb.is_null());
   CHECK(read_cb_.is_null()) << "Overlapping decodes are not supported.";
   read_cb_ = BindToCurrentLoop(read_cb);
 
@@ skipping 84 matching lines @@
   DCHECK_EQ(state_, kDecryptorRequested) << state_;
   DCHECK(!init_cb_.is_null());
   DCHECK(!set_decryptor_ready_cb_.is_null());
   set_decryptor_ready_cb_.Reset();
 
   decryptor_ = decryptor;
 
   state_ = kPendingDecoderInit;
   decryptor_->InitializeVideoDecoder(
       demuxer_stream_->video_decoder_config(), BindToCurrentLoop(base::Bind(
-          &DecryptingVideoDecoder::FinishInitialization, this)));
+          &DecryptingVideoDecoder::FinishInitialization, weak_this_)));
 }
 
 void DecryptingVideoDecoder::FinishInitialization(bool success) {
   DVLOG(2) << "FinishInitialization()";
   DCHECK(message_loop_->BelongsToCurrentThread());
 
   if (state_ == kStopped)
     return;
 
   DCHECK_EQ(state_, kPendingDecoderInit) << state_;
   DCHECK(!init_cb_.is_null());
   DCHECK(reset_cb_.is_null());  // No Reset() before initialization finished.
   DCHECK(read_cb_.is_null());  // No Read() before initialization finished.
 
   if (!success) {
     base::ResetAndReturn(&init_cb_).Run(DECODER_ERROR_NOT_SUPPORTED);
     state_ = kStopped;
     return;
   }
 
   decryptor_->RegisterNewKeyCB(Decryptor::kVideo, BindToCurrentLoop(
-      base::Bind(&DecryptingVideoDecoder::OnKeyAdded, this)));
+      base::Bind(&DecryptingVideoDecoder::OnKeyAdded, weak_this_)));
 
   // Success!
   state_ = kIdle;
   base::ResetAndReturn(&init_cb_).Run(PIPELINE_OK);
 }
 
 void DecryptingVideoDecoder::FinishConfigChange(bool success) {
   DVLOG(2) << "FinishConfigChange()";
   DCHECK(message_loop_->BelongsToCurrentThread());
 
@@ skipping 21 matching lines @@
   state_ = kPendingDemuxerRead;
   ReadFromDemuxerStream();
 }
 
 void DecryptingVideoDecoder::ReadFromDemuxerStream() {
   DCHECK(message_loop_->BelongsToCurrentThread());
   DCHECK_EQ(state_, kPendingDemuxerRead) << state_;
   DCHECK(!read_cb_.is_null());
 
   demuxer_stream_->Read(
-      base::Bind(&DecryptingVideoDecoder::DecryptAndDecodeBuffer, this));
+      base::Bind(&DecryptingVideoDecoder::DecryptAndDecodeBuffer, weak_this_));

[Ami GONE FROM CHROMIUM, 2013/03/22 23:48:01]

What guarantees you get called back on this thread?  (which is required for
reading weak_this_ to be legit).
IOW do you want s/Bind/BindToCurrentLoop/?

[scherkus (not reviewing), 2013/03/28 02:00:01]

short term: it's part of the API contract to call back async-ly and on the
calling thread

medium term: xhwang is in the midst of having video decoders not make async
calls to demuxers, so this code will go away

 }
 
 void DecryptingVideoDecoder::DecryptAndDecodeBuffer(
     DemuxerStream::Status status,
     const scoped_refptr<DecoderBuffer>& buffer) {
   DVLOG(3) << "DecryptAndDecodeBuffer()";
   DCHECK(message_loop_->BelongsToCurrentThread());
 
   if (state_ == kStopped)
     return;
 
   DCHECK_EQ(state_, kPendingDemuxerRead) << state_;
   DCHECK(!read_cb_.is_null());
   DCHECK_EQ(buffer != NULL, status == DemuxerStream::kOk) << status;
 
   if (status == DemuxerStream::kConfigChanged) {
     DVLOG(2) << "DecryptAndDecodeBuffer() - kConfigChanged";
 
     state_ = kPendingConfigChange;
     decryptor_->DeinitializeDecoder(Decryptor::kVideo);
     decryptor_->InitializeVideoDecoder(
         demuxer_stream_->video_decoder_config(), BindToCurrentLoop(base::Bind(
-            &DecryptingVideoDecoder::FinishConfigChange, this)));
+            &DecryptingVideoDecoder::FinishConfigChange, weak_this_)));
     return;
   }
 
   if (!reset_cb_.is_null()) {
     base::ResetAndReturn(&read_cb_).Run(kOk, NULL);
     DoReset();
     return;
   }
 
   if (status == DemuxerStream::kAborted) {
@@ skipping 15 matching lines @@
   TRACE_EVENT_ASYNC_BEGIN0(
       "eme", "DecryptingVideoDecoder::DecodePendingBuffer", ++trace_id_);
 
   int buffer_size = 0;
   if (!pending_buffer_to_decode_->IsEndOfStream()) {
     buffer_size = pending_buffer_to_decode_->GetDataSize();
   }
 
   decryptor_->DecryptAndDecodeVideo(
       pending_buffer_to_decode_, BindToCurrentLoop(base::Bind(
-          &DecryptingVideoDecoder::DeliverFrame, this, buffer_size)));
+          &DecryptingVideoDecoder::DeliverFrame, weak_this_, buffer_size)));
 }
 
 void DecryptingVideoDecoder::DeliverFrame(
     int buffer_size,
     Decryptor::Status status,
     const scoped_refptr<VideoFrame>& frame) {
   DVLOG(3) << "DeliverFrame() - status: " << status;
   DCHECK(message_loop_->BelongsToCurrentThread());
   TRACE_EVENT_ASYNC_END0(
       "eme", "DecryptingVideoDecoder::DecodePendingBuffer", trace_id_);
@@ skipping 87 matching lines @@
 }
 
 void DecryptingVideoDecoder::DoReset() {
   DCHECK(init_cb_.is_null());
   DCHECK(read_cb_.is_null());
   state_ = kIdle;
   base::ResetAndReturn(&reset_cb_).Run();
 }
 
 }  // namespace media