--- a/media/webrtc/trunk/webrtc/modules/desktop_capture/screen_capturer_mac.mm
+++ b/media/webrtc/trunk/webrtc/modules/desktop_capture/screen_capturer_mac.mm
@@ -358,16 +358,23 @@ class ScreenCapturerMac : public Desktop
   CGLSetFullScreenFunc cgl_set_full_screen_ = nullptr;
 
   CGWindowID excluded_window_ = 0;
 
   // A self-owned object that will destroy itself after ScreenCapturerMac and
   // all display streams have been destroyed..
   DisplayStreamManager* display_stream_manager_;
 
+  // Used to force CaptureFrame to update it's screen configuration
+  // and reregister event handlers. This ensure that this
+  // occurs on the ScreenCapture thread. Read and written from
+  // both the VideoCapture thread and ScreenCapture thread.
+  // Protected by desktop_config_monitor_.
+  bool update_screen_configuration_ = false;
+
   RTC_DISALLOW_COPY_AND_ASSIGN(ScreenCapturerMac);
 };
 
 // DesktopFrame wrapper that flips wrapped frame upside down by inverting
 // stride.
 class InvertedDesktopFrame : public DesktopFrame {
  public:
   InvertedDesktopFrame(std::unique_ptr<DesktopFrame> frame)
@@ -398,23 +405,32 @@ ScreenCapturerMac::ScreenCapturerMac(
 ScreenCapturerMac::~ScreenCapturerMac() {
   ReleaseBuffers();
   display_stream_manager_->PrepareForSelfDestruction();
   dlclose(app_services_library_);
   dlclose(opengl_library_);
 }
 
 bool ScreenCapturerMac::Init() {
+// MOZILLA: Calling RegisterRefreshAndMoveHandlers here causes us
+// to register on the VideoCapture thread rather than the ScreenCapture
+// thread which will result in us never receiving any notifications.
+// See Bug 1468509.
+/*
   desktop_config_monitor_->Lock();
   desktop_config_ = desktop_config_monitor_->desktop_configuration();
   desktop_config_monitor_->Unlock();
   if (!RegisterRefreshAndMoveHandlers()) {
     return false;
   }
   ScreenConfigurationChanged();
+*/
+  desktop_config_monitor_->Lock();
+  update_screen_configuration_ = true;
+  desktop_config_monitor_->Unlock();
   return true;
 }
 
 void ScreenCapturerMac::ReleaseBuffers() {
   if (cgl_context_) {
     pixel_buffer_object_.Release();
     CGLDestroyContext(cgl_context_);
     cgl_context_ = nullptr;
@@ -425,16 +441,19 @@ void ScreenCapturerMac::ReleaseBuffers()
   queue_.Reset();
 }
 
 void ScreenCapturerMac::Start(Callback* callback) {
   assert(!callback_);
   assert(callback);
 
   callback_ = callback;
+  desktop_config_monitor_->Lock();
+  update_screen_configuration_ = true;
+  desktop_config_monitor_->Unlock();
 }
 
 void ScreenCapturerMac::Stop() {
   if (power_assertion_id_display_ != kIOPMNullAssertionID) {
     IOPMAssertionRelease(power_assertion_id_display_);
     power_assertion_id_display_ = kIOPMNullAssertionID;
   }
   if (power_assertion_id_user_ != kIOPMNullAssertionID) {
@@ -443,23 +462,27 @@ void ScreenCapturerMac::Stop() {
   }
 
   callback_ = NULL;
 }
 
 void ScreenCapturerMac::CaptureFrame() {
   int64_t capture_start_time_nanos = rtc::TimeNanos();
 
+  // Spin RunLoop for 1/100th of a second, handling at most one source
+  CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.01, true);
+
   queue_.MoveToNextFrame();
   RTC_DCHECK(!queue_.current_frame() || !queue_.current_frame()->IsShared());
 
   desktop_config_monitor_->Lock();
   MacDesktopConfiguration new_config =
       desktop_config_monitor_->desktop_configuration();
-  if (!desktop_config_.Equals(new_config)) {
+  if (update_screen_configuration_ || !desktop_config_.Equals(new_config)) {
+    update_screen_configuration_ = false;
     desktop_config_ = new_config;
     // If the display configuraiton has changed then refresh capturer data
     // structures. Occasionally, the refresh and move handlers are lost when
     // the screen mode changes, so re-register them here.
     UnregisterRefreshAndMoveHandlers();
     RegisterRefreshAndMoveHandlers();
     ScreenConfigurationChanged();
   }