refactor video capture in browser process to support device sharing across multiple renderer proc...

content/browser/renderer_host/media/video_capture_controller.cc

 // Copyright (c) 2011 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 "content/browser/renderer_host/media/video_capture_controller.h"
 
 #include "base/bind.h"
 #include "base/stl_util.h"
 #include "content/browser/renderer_host/media/media_stream_manager.h"
 #include "content/browser/renderer_host/media/video_capture_manager.h"
 #include "content/public/browser/browser_thread.h"
 #include "media/base/yuv_convert.h"
 
-// The number of TransportDIBs VideoCaptureController allocate.
+// The number of DIBs VideoCaptureController allocate.
 static const size_t kNoOfDIBS = 3;
 
+struct VideoCaptureController::ControllerClient {
+  ControllerClient(
+      const VideoCaptureControllerID& id,
+      VideoCaptureControllerEventHandler* handler,
+      base::ProcessHandle render_process,
+      const media::VideoCaptureParams& params)
+      : controller_id(id),
+        event_handler(handler),
+        render_process_handle(render_process),
+        parameters(params),
+        report_ready_to_delete(false) {
+  }
+
+  ~ControllerClient() {}
+
+  // ID used for identifying this object.
+  VideoCaptureControllerID controller_id;
+  VideoCaptureControllerEventHandler* event_handler;
+
+  // Handle to the render process that will receive the DIBs.
+  base::ProcessHandle render_process_handle;
+  media::VideoCaptureParams parameters;
+
+  // Buffers used by this client.
+  std::list<int> buffers;
+
+  // Record client's status when it has called StopCapture, but haven't
+  // returned all buffers.
+  bool report_ready_to_delete;
+};
+
+struct VideoCaptureController::SharedDIB {
+  SharedDIB(base::SharedMemory* ptr)
+      : shared_memory(ptr),
+        references(0) {
+  }
+
+  ~SharedDIB() {}
+
+  // The memory created to be shared with renderer processes.
+  scoped_ptr<base::SharedMemory> shared_memory;
+
+  // Number of renderer processes which hold this shared memory.
+  // renderer process is represented by VidoeCaptureHost.
+  int references;
+};
+
 VideoCaptureController::VideoCaptureController(
-    const VideoCaptureControllerID& id,
-    base::ProcessHandle render_process,
-    VideoCaptureControllerEventHandler* event_handler,
     media_stream::VideoCaptureManager* video_capture_manager)
-    : render_handle_(render_process),
-      report_ready_to_delete_(false),
-      event_handler_(event_handler),
-      id_(id),
-      video_capture_manager_(video_capture_manager) {
-  memset(&params_, 0, sizeof(params_));
+    : frame_info_available_(false),
+      video_capture_manager_(video_capture_manager),
+      device_in_use_(false),
+      state_(media::VideoCapture::kStopped) {
+  memset(&current_params_, 0, sizeof(current_params_));
 }
 
 VideoCaptureController::~VideoCaptureController() {
-  // Delete all TransportDIBs.
+  // Delete all DIBs.
   STLDeleteContainerPairSecondPointers(owned_dibs_.begin(),
                                        owned_dibs_.end());
+  STLDeleteContainerPointers(controller_clients_.begin(),
+                             controller_clients_.end());
+  STLDeleteContainerPointers(pending_clients_.begin(),
+                             pending_clients_.end());
 }
 
 void VideoCaptureController::StartCapture(
+    const VideoCaptureControllerID& id,
+    VideoCaptureControllerEventHandler* event_handler,
+    base::ProcessHandle render_process,
     const media::VideoCaptureParams& params) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-
-  params_ = params;
+  // Signal error in case device is already in error state.
+  if (state_ == media::VideoCapture::kError) {
+    event_handler->OnError(id);
+    return;
+  }
+
+  // Do nothing if this client has called StartCapture before.
+  if (FindClient(id, event_handler, controller_clients_) ||
+      FindClient(id, event_handler, pending_clients_))
+    return;
+
+  ControllerClient* client = new ControllerClient(id, event_handler,
+                                                  render_process, params);
+  // In case capture has been started, need to check different condtions.
+  if (state_ == media::VideoCapture::kStarted) {
+    // This client has higher resolution than what is currently requested.
+    // Need restart capturing.
+    if (params.width > current_params_.width ||
+        params.height > current_params_.height) {
+      video_capture_manager_->Stop(current_params_.session_id,
+          base::Bind(&VideoCaptureController::OnDeviceStopped, this));
+      frame_info_available_ = false;
+      state_ = media::VideoCapture::kStopping;
+      pending_clients_.push_back(client);
+      return;
+    }
+
+    // This client's resolution is no larger than what's currently requested.
+    // When frame_info has been returned by device, send them to client.
+    if (frame_info_available_) {
+      int buffer_size = (frame_info_.width * frame_info_.height * 3) / 2;
+      SendFrameInfoAndBuffers(client, buffer_size);
+    }
+    controller_clients_.push_back(client);
+    return;
+  }
+
+  // In case the device is in the middle of stopping, put the client in
+  // pending queue.
+  if (state_ == media::VideoCapture::kStopping) {
+    pending_clients_.push_back(client);
+    return;
+  }
+
+  // Fresh start.
+  controller_clients_.push_back(client);
+  current_params_ = params;
   // Order the manager to start the actual capture.
   video_capture_manager_->Start(params, this);
-}
-
-void VideoCaptureController::StopCapture(base::Closure stopped_cb) {
+  state_ = media::VideoCapture::kStarted;
+}
+
+void VideoCaptureController::StopCapture(
+    const VideoCaptureControllerID& id,
+    VideoCaptureControllerEventHandler* event_handler,
+    bool force_buffer_return) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
-  video_capture_manager_->Stop(params_.session_id,
-      base::Bind(&VideoCaptureController::OnDeviceStopped, this, stopped_cb));
-}
-
-void VideoCaptureController::ReturnBuffer(int buffer_id) {
+  ControllerClient* client = FindClient(id, event_handler, pending_clients_);
+  // If the client is still in pending queue, just remove it.
+  if (client) {
+    client->event_handler->OnReadyToDelete(client->controller_id);
+    pending_clients_.remove(client);
+    return;
+  }
+
+  client = FindClient(id, event_handler, controller_clients_);
+  DCHECK(client) << "Client should have called StartCapture()";
+
+  if (force_buffer_return) {
+    // The client requests to return buffers which means it can't return
+    // buffers normally. After buffers are returned, client is free to
+    // delete itself. No need to call OnReadyToDelete.
+
+    // Return all buffers held by the clients.
+    for (std::list<int>::iterator buffer_it = client->buffers.begin();
+         buffer_it != client->buffers.end(); ++buffer_it) {
+      int buffer_id = *buffer_it;
+      DIBMap::iterator dib_it = owned_dibs_.find(buffer_id);
+      if (dib_it == owned_dibs_.end())
+        continue;
+
+      {
+        base::AutoLock lock(lock_);
+        DCHECK_GT(dib_it->second->references, 0) << "The buffer is not used by "

[scherkus (not reviewing), 2011/11/02 23:08:26]

nit: drop the << to 4-space indent on next line

[wjia(left Chromium), 2011/11/03 07:02:02]

Done.

+                                                 << "renderer";
+        dib_it->second->references -= 1;
+      }
+    }
+    client->buffers.clear();
+  } else {
+    // Normal way to stop capture.
+    if (!client->buffers.empty()) {
+      // There are still some buffers held by the client.
+      client->report_ready_to_delete = true;
+      return;
+    }
+    // No buffer is held by the client. Ready to delete.
+    client->event_handler->OnReadyToDelete(client->controller_id);
+  }
+
+  delete client;
+  controller_clients_.remove(client);
+
+  // No more clients. Stop device.
+  if (controller_clients_.empty()) {
+    video_capture_manager_->Stop(current_params_.session_id,
+        base::Bind(&VideoCaptureController::OnDeviceStopped, this));
+    frame_info_available_ = false;
+    state_ = media::VideoCapture::kStopping;
+  }
+}
+
+void VideoCaptureController::ReturnBuffer(
+    const VideoCaptureControllerID& id,
+    VideoCaptureControllerEventHandler* event_handler,
+    int buffer_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
-  bool ready_to_delete;
+  ControllerClient* client = FindClient(id, event_handler,
+                                        controller_clients_);
+  DIBMap::iterator dib_it = owned_dibs_.find(buffer_id);
+  // If this buffer is not held by this client, or this client doesn't exist
+  // in controller, do nothing.
+  if (!client || dib_it == owned_dibs_.end())
+    return;
+
+  client->buffers.remove(buffer_id);
+  // If this client has called StopCapture and doesn't hold any buffer after
+  // after this return, ready to delete this client.
+  if (client->report_ready_to_delete && client->buffers.empty()) {
+    client->event_handler->OnReadyToDelete(client->controller_id);
+    delete client;
+    controller_clients_.remove(client);
+  }
   {
     base::AutoLock lock(lock_);
-    free_dibs_.push_back(buffer_id);
-    ready_to_delete = (free_dibs_.size() == owned_dibs_.size()) &&
-        report_ready_to_delete_;
-  }
-  if (ready_to_delete) {
-    event_handler_->OnReadyToDelete(id_);
-  }
-}
-
+    DCHECK_GT(dib_it->second->references, 0) << "The buffer is not used by "

[scherkus (not reviewing), 2011/11/02 23:08:26]

ditto

[wjia(left Chromium), 2011/11/03 07:02:02]

Done.

+                                             << "renderer";
+    dib_it->second->references -= 1;
+    if (dib_it->second->references > 0)
+      return;
+  }
+
+  // When all buffers have been returned by clients and device has been
+  // called to stop, check if restart is needed. This could happen when
+  // some clients call StopCapture before returning all buffers.
+  if (!ClientHasDIB() && state_ == media::VideoCapture::kStopping) {
+    PostStopping();
+  }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Implements VideoCaptureDevice::EventHandler.
 // OnIncomingCapturedFrame is called the thread running the capture device.
 // I.e.- DirectShow thread on windows and v4l2_thread on Linux.
 void VideoCaptureController::OnIncomingCapturedFrame(const uint8* data,
                                                      int length,
                                                      base::Time timestamp) {
   int buffer_id = 0;
   base::SharedMemory* dib = NULL;
-  // Check if there is a TransportDIB to fill.
-  bool buffer_exist = false;
   {
     base::AutoLock lock(lock_);
-    if (!report_ready_to_delete_ && free_dibs_.size() > 0) {
-      buffer_id = free_dibs_.front();
-      free_dibs_.pop_front();
-      DIBMap::iterator it = owned_dibs_.find(buffer_id);
-      if (it != owned_dibs_.end()) {
-        dib = it->second;
-        buffer_exist = true;
+    for (DIBMap::iterator dib_it = owned_dibs_.begin();
+         dib_it != owned_dibs_.end(); dib_it++) {
+      if (dib_it->second->references == 0) {
+        buffer_id = dib_it->first;
+        // Use special value "-1" in order to not be treated as buffer at
+        // renderer side.
+        dib_it->second->references = -1;

[scherkus (not reviewing), 2011/11/02 23:08:26]

does setting it as 1 really cause things to go wrong?

if not, then keeping reference count non-negative would certainly be clearer but
if so could we make this a constant?

I also wonder whether it makes sense to make SharedDIB a class as opposed to a
struct. For example you could have AddRef() and Release() methods, DCHECKs,
etc...

Your call.

[wjia(left Chromium), 2011/11/03 07:02:02]

yes, setting it as 1 indeed confuses ClientHasDIB().

I will keep an eye on SharedDIB for future improvement. Right now, controller
has exclusive ownership of this struct.

+        dib = dib_it->second->shared_memory.get();
+        break;
       }
     }
   }
 
-  if (!buffer_exist) {
+  if (!dib) {
     return;
   }
 
   uint8* target = static_cast<uint8*>(dib->memory());
   CHECK(dib->created_size() >= static_cast<size_t> (frame_info_.width *
                                                     frame_info_.height * 3) /
                                                     2);
+  uint8* yplane = target;
+  uint8* uplane = target + frame_info_.width * frame_info_.height;
+  uint8* vplane = uplane + (frame_info_.width * frame_info_.height) / 4;
 
   // Do color conversion from the camera format to I420.
   switch (frame_info_.color) {
     case media::VideoCaptureDevice::kColorUnknown:  // Color format not set.
       break;
     case media::VideoCaptureDevice::kI420: {
       memcpy(target, data, (frame_info_.width * frame_info_.height * 3) / 2);
       break;
     }
     case media::VideoCaptureDevice::kYUY2: {
-      uint8* yplane = target;
-      uint8* uplane = target + frame_info_.width * frame_info_.height;
-      uint8* vplane = uplane + (frame_info_.width * frame_info_.height) / 4;
       media::ConvertYUY2ToYUV(data, yplane, uplane, vplane, frame_info_.width,
                               frame_info_.height);
       break;
     }
     case media::VideoCaptureDevice::kRGB24: {
-#if defined(OS_WIN)  // RGB on Windows start at the bottom line.
-      uint8* yplane = target;
-      uint8* uplane = target + frame_info_.width * frame_info_.height;
-      uint8* vplane = uplane + (frame_info_.width * frame_info_.height) / 4;
       int ystride = frame_info_.width;
       int uvstride = frame_info_.width / 2;
-      int rgb_stride = - 3 * frame_info_.width;
+#if defined(OS_WIN)  // RGB on Windows start at the bottom line.
+      int rgb_stride = -3 * frame_info_.width;
       const uint8* rgb_src = data + 3 * frame_info_.width *
           (frame_info_.height -1);
 #else
-      uint8* yplane = target;
-      uint8* uplane = target + frame_info_.width * frame_info_.height;
-      uint8* vplane = uplane + (frame_info_.width * frame_info_.height) / 4;
-      int ystride = frame_info_.width;
-      int uvstride = frame_info_.width / 2;
       int rgb_stride = 3 * frame_info_.width;
       const uint8* rgb_src = data;
 #endif
       media::ConvertRGB24ToYUV(rgb_src, yplane, uplane, vplane,
                                frame_info_.width, frame_info_.height,
                                rgb_stride, ystride, uvstride);
       break;
     }
     case media::VideoCaptureDevice::kARGB: {
-      uint8* yplane = target;
-      uint8* uplane = target +  frame_info_.width * frame_info_.height;
-      uint8* vplane = uplane +  (frame_info_.width * frame_info_.height) / 4;
       media::ConvertRGB32ToYUV(data, yplane, uplane, vplane, frame_info_.width,
                                frame_info_.height, frame_info_.width * 4,
                                frame_info_.width, frame_info_.width / 2);
       break;
     }
     default:
       NOTREACHED();
   }
 
-  event_handler_->OnBufferReady(id_, buffer_id, timestamp);
+  BrowserThread::PostTask(BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&VideoCaptureController::DoIncomingCapturedFrameOnIOThread,
+                 this, buffer_id, timestamp));
 }
 
 void VideoCaptureController::OnError() {
-  event_handler_->OnError(id_);
-  video_capture_manager_->Error(params_.session_id);
+  video_capture_manager_->Error(current_params_.session_id);
+  BrowserThread::PostTask(BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&VideoCaptureController::DoErrorOnIOThread, this));
 }
 
 void VideoCaptureController::OnFrameInfo(
     const media::VideoCaptureDevice::Capability& info) {
-  DCHECK(owned_dibs_.empty());
+  BrowserThread::PostTask(BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&VideoCaptureController::DoFrameInfoOnIOThread,
+                 this, info));
+}
+
+void VideoCaptureController::DoIncomingCapturedFrameOnIOThread(
+    int buffer_id, base::Time timestamp) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  int count = 0;
+  if (state_ == media::VideoCapture::kStarted) {
+    for (ControllerClients::iterator client_it = controller_clients_.begin();
+         client_it != controller_clients_.end(); client_it++) {
+      if ((*client_it)->report_ready_to_delete)
+        continue;
+
+      (*client_it)->event_handler->OnBufferReady((*client_it)->controller_id,
+                                                 buffer_id, timestamp);
+      (*client_it)->buffers.push_back(buffer_id);
+      count++;
+    }
+  }
+
+  base::AutoLock lock(lock_);
+  DCHECK_EQ(owned_dibs_[buffer_id]->references, -1);
+  owned_dibs_[buffer_id]->references = count;
+}
+
+void VideoCaptureController::DoErrorOnIOThread() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  state_ = media::VideoCapture::kError;
+  ControllerClients::iterator client_it;
+  for (client_it = controller_clients_.begin();
+       client_it != controller_clients_.end(); client_it++) {
+    (*client_it)->event_handler->OnError((*client_it)->controller_id);
+  }
+  for (client_it = pending_clients_.begin();
+       client_it != pending_clients_.end(); client_it++) {
+    (*client_it)->event_handler->OnError((*client_it)->controller_id);
+  }
+}
+
+void VideoCaptureController::DoFrameInfoOnIOThread(
+    const media::VideoCaptureDevice::Capability info) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK(owned_dibs_.empty()) << "Device is restarted without releasing shared "

[scherkus (not reviewing), 2011/11/02 23:08:26]

ditto

[wjia(left Chromium), 2011/11/03 07:02:02]

Done.

+                              << "memory.";
+
   bool frames_created = true;
   const size_t needed_size = (info.width * info.height * 3) / 2;
-  for (size_t i = 1; i <= kNoOfDIBS; ++i) {
-    base::SharedMemory* shared_memory = new base::SharedMemory();
-    if (!shared_memory->CreateAndMapAnonymous(needed_size)) {
-      frames_created = false;
-      break;
-    }
+  {
+    base::AutoLock lock(lock_);
+    for (size_t i = 1; i <= kNoOfDIBS; ++i) {
+      base::SharedMemory* shared_memory = new base::SharedMemory();
+      if (!shared_memory->CreateAndMapAnonymous(needed_size)) {
+        frames_created = false;
+        break;
+      }
+      SharedDIB* dib = new SharedDIB(shared_memory);
+      owned_dibs_.insert(std::make_pair(i, dib));
+    }
+  }
+  // Check whether all DIBs were created successfully.
+  if (!frames_created) {
+    state_ = media::VideoCapture::kError;
+    for (ControllerClients::iterator client_it = controller_clients_.begin();
+         client_it != controller_clients_.end(); client_it++) {
+      (*client_it)->event_handler->OnError((*client_it)->controller_id);
+    }
+    return;
+  }
+  frame_info_= info;
+  frame_info_available_ = true;
+
+  for (ControllerClients::iterator client_it = controller_clients_.begin();
+       client_it != controller_clients_.end(); client_it++) {
+    SendFrameInfoAndBuffers((*client_it), static_cast<int>(needed_size));
+  }
+}
+
+void VideoCaptureController::SendFrameInfoAndBuffers(
+    ControllerClient* client, int buffer_size) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK(frame_info_available_);
+  client->event_handler->OnFrameInfo(client->controller_id,
+                                     frame_info_.width, frame_info_.height,
+                                     frame_info_.frame_rate);
+  for (DIBMap::iterator dib_it = owned_dibs_.begin();
+       dib_it != owned_dibs_.end(); dib_it++) {
+    base::SharedMemory* shared_memory = dib_it->second->shared_memory.get();
+    int index = dib_it->first;
     base::SharedMemoryHandle remote_handle;
-    shared_memory->ShareToProcess(render_handle_, &remote_handle);
-
-    base::AutoLock lock(lock_);
-    owned_dibs_.insert(std::make_pair(i, shared_memory));
-    free_dibs_.push_back(i);
-    event_handler_->OnBufferCreated(id_, remote_handle,
-                                    static_cast<int>(needed_size),
-                                    static_cast<int>(i));
-  }
-  frame_info_= info;
-
-  // Check that all DIBs where created successfully.
-  if (!frames_created) {
-    event_handler_->OnError(id_);
-  }
-  event_handler_->OnFrameInfo(id_, info.width, info.height, info.frame_rate);
+    shared_memory->ShareToProcess(client->render_process_handle,
+                                  &remote_handle);
+    client->event_handler->OnBufferCreated(client->controller_id,
+                                           remote_handle,
+                                           buffer_size,
+                                           index);
+  }
+}
+
+// This function is called when all buffers have been returned to controller,
+// or when device is stopped. It decides whether the device needs to be
+// restarted.
+void VideoCaptureController::PostStopping() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK_EQ(state_, media::VideoCapture::kStopping);
+
+  // When clients still have some buffers, or device has not been stopped yet,
+  // do nothing.
+  if (ClientHasDIB() || device_in_use_)
+    return;
+
+  // It's safe to free all DIB's on IO thread since device won't send
+  // buffer over.
+  STLDeleteValues(&owned_dibs_);
+
+  // No more client. Therefore the controller is stopped.
+  if (controller_clients_.empty() && pending_clients_.empty()) {
+    state_ = media::VideoCapture::kStopped;
+    return;
+  }
+
+  // Restart the device.
+  current_params_.width = 0;
+  current_params_.height = 0;
+  ControllerClients::iterator client_it;
+  for (client_it = controller_clients_.begin();
+       client_it != controller_clients_.end(); client_it++) {
+    if (current_params_.width < (*client_it)->parameters.width)
+      current_params_.width = (*client_it)->parameters.width;
+    if (current_params_.height < (*client_it)->parameters.height)
+      current_params_.height = (*client_it)->parameters.height;
+  }
+  for (client_it = pending_clients_.begin();
+       client_it != pending_clients_.end(); ) {
+    if (current_params_.width < (*client_it)->parameters.width)
+      current_params_.width = (*client_it)->parameters.width;
+    if (current_params_.height < (*client_it)->parameters.height)
+      current_params_.height = (*client_it)->parameters.height;
+    controller_clients_.push_back((*client_it));
+    pending_clients_.erase(client_it++);
+  }
+  // Request the manager to start the actual capture.
+  video_capture_manager_->Start(current_params_, this);
+  state_ = media::VideoCapture::kStarted;
+}
+
+bool VideoCaptureController::ClientHasDIB() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  base::AutoLock lock(lock_);
+  for (DIBMap::iterator dib_it = owned_dibs_.begin();
+       dib_it != owned_dibs_.end(); dib_it++) {
+    if (dib_it->second->references > 0)
+      return true;
+  }
+  return false;
+}
+
+VideoCaptureController::ControllerClient*
+VideoCaptureController::FindClient(
+    const VideoCaptureControllerID& id,
+    VideoCaptureControllerEventHandler* handler,
+    ControllerClients& clients) {
+  for (ControllerClients::iterator client_it = clients.begin();
+       client_it != clients.end(); client_it++) {
+    if ((*client_it)->controller_id == id &&
+        (*client_it)->event_handler == handler) {
+      return *client_it;
+    }
+  }
+  return NULL;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // Called by VideoCaptureManager when a device have been stopped.
-// This will report to the event handler that this object is ready to be deleted
-// if all DIBS have been returned.
-void VideoCaptureController::OnDeviceStopped(base::Closure stopped_cb) {
-  bool ready_to_delete_now;
-
-  {
-    base::AutoLock lock(lock_);
-    // Set flag to indicate we need to report when all DIBs have been returned.
-    report_ready_to_delete_ = true;
-    ready_to_delete_now = (free_dibs_.size() == owned_dibs_.size());
-  }
-
-  if (ready_to_delete_now) {
-    event_handler_->OnReadyToDelete(id_);
-  }
-
-  if (!stopped_cb.is_null())
-    stopped_cb.Run();
-}
+void VideoCaptureController::OnDeviceStopped() {
+  BrowserThread::PostTask(BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&VideoCaptureController::DoDeviceStoppedOnIOThread, this));
+}
+
+void VideoCaptureController::DoDeviceStoppedOnIOThread() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  device_in_use_ = false;
+  if (state_ == media::VideoCapture::kStopping) {
+    PostStopping();
+  }
+}
+