--- a/dom/media/systemservices/VideoEngine.cpp
+++ b/dom/media/systemservices/VideoEngine.cpp
@@ -63,19 +63,35 @@ VideoEngine::CreateVideoCapture(int32_t&
 
   CaptureEntry entry = {-1, nullptr};
 
   if (mCaptureDevInfo.type == webrtc::CaptureDeviceType::Camera) {
     entry = CaptureEntry(id,
 		         webrtc::VideoCaptureFactory::Create(deviceUniqueIdUTF8));
   } else {
 #ifndef WEBRTC_ANDROID
+#ifdef MOZ_X11
+    webrtc::VideoCaptureModule* captureModule;
+    auto type = mCaptureDevInfo.type;
+    nsresult result = NS_DispatchToMainThread(media::NewRunnableFrom(
+      [&captureModule, id, deviceUniqueIdUTF8, type]() -> nsresult {
+        captureModule = webrtc::DesktopCaptureImpl::Create(id, deviceUniqueIdUTF8, type);
+        return NS_OK;
+      }), nsIEventTarget::DISPATCH_SYNC);
+
+    if (result == NS_OK) {
+      entry = CaptureEntry(id, captureModule);
+    } else {
+      return;
+    }
+#else
     entry = CaptureEntry(
 	      id,
 	      webrtc::DesktopCaptureImpl::Create(id, deviceUniqueIdUTF8, mCaptureDevInfo.type));
+#endif
 #else
     MOZ_ASSERT("CreateVideoCapture NO DESKTOP CAPTURE IMPL ON ANDROID" == nullptr);
 #endif
   }
   mCaps.emplace(id, std::move(entry));
   mIdMap.emplace(id, id);
 }
 

--- a/media/webrtc/trunk/webrtc/video_engine/desktop_capture_impl.cc
+++ b/media/webrtc/trunk/webrtc/video_engine/desktop_capture_impl.cc
@@ -443,33 +443,38 @@ DesktopCaptureImpl::DesktopCaptureImpl(c
     // XXX Note that this won't capture drift!
     delta_ntp_internal_ms_(Clock::GetRealTimeClock()->CurrentNtpInMilliseconds() -
                            last_capture_time_),
     time_event_(EventWrapper::Create()),
     mRefCount(0),
 #if defined(_WIN32)
     capturer_thread_(new rtc::PlatformUIThread(Run, this, "ScreenCaptureThread")),
 #else
+#if defined(WEBRTC_LINUX)
+    capturer_thread_(nullptr),
+#else
     capturer_thread_(new rtc::PlatformThread(Run, this, "ScreenCaptureThread")),
 #endif
+#endif
     started_(false) {
   //-> TODO @@NG why is this crashing (seen on Linux)
   //-> capturer_thread_->SetPriority(rtc::kHighPriority);
   _requestedCapability.width = kDefaultWidth;
   _requestedCapability.height = kDefaultHeight;
   _requestedCapability.maxFPS = 30;
   _requestedCapability.rawType = kVideoI420;
   _requestedCapability.codecType = kVideoCodecUnknown;
   memset(_incomingFrameTimesNanos, 0, sizeof(_incomingFrameTimesNanos));
 }
 
 DesktopCaptureImpl::~DesktopCaptureImpl() {
   time_event_->Set();
-  capturer_thread_->Stop();
-
+  if (capturer_thread_) {
+    capturer_thread_->Stop();
+  }
   delete &_callBackCs;
   delete &_apiCs;
 }
 
 void DesktopCaptureImpl::RegisterCaptureDataCallback(rtc::VideoSinkInterface<VideoFrame> *dataCallback)
 {
   CriticalSectionScoped cs(&_apiCs);
   CriticalSectionScoped cs2(&_callBackCs);
@@ -659,17 +664,23 @@ int32_t DesktopCaptureImpl::StartCapture
 #if defined(_WIN32)
   uint32_t maxFPSNeeded = 1000/_requestedCapability.maxFPS;
   capturer_thread_->RequestCallbackTimer(maxFPSNeeded);
 #endif
 
   if (started_) {
     return 0;
   }
-
+#if defined(WEBRTC_LINUX)
+  // Lazily init capturer_thread_
+  if (!capturer_thread_) {
+      capturer_thread_ = std::unique_ptr<rtc::PlatformThread>(
+          new rtc::PlatformThread(Run, this, "ScreenCaptureThread"));
+  }
+#endif
   desktop_capturer_cursor_composer_->Start(this);
   capturer_thread_->Start();
   started_ = true;
 
   return 0;
 }
 
 bool DesktopCaptureImpl::FocusOnSelectedSource()