Fix up Curtain mode on MacOS 10.7

remoting/host/capturer_mac.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 "remoting/host/capturer.h"
 
 #include <ApplicationServices/ApplicationServices.h>
 #include <dlfcn.h>
 #include <OpenGL/CGLMacro.h>
 #include <OpenGL/OpenGL.h>
@@ skipping 210 matching lines @@
       last_buffer_(NULL),
       pixel_format_(media::VideoFrame::RGB32),
       display_configuration_capture_event_(false, true),
       display_create_image_func_(NULL) {
 }
 
 CapturerMac::~CapturerMac() {
   ReleaseBuffers();
   CGUnregisterScreenRefreshCallback(CapturerMac::ScreenRefreshCallback, this);
   CGScreenUnregisterMoveCallback(CapturerMac::ScreenUpdateMoveCallback, this);
-  CGDisplayRemoveReconfigurationCallback(
+  CGError err = CGDisplayRemoveReconfigurationCallback(
       CapturerMac::DisplaysReconfiguredCallback, this);
+  if (err != kCGErrorSuccess) {
+    LOG(ERROR) << "CGDisplayRemoveReconfigurationCallback " << err;
+  }
 }
 
 bool CapturerMac::Init() {
   CGError err =
       CGRegisterScreenRefreshCallback(CapturerMac::ScreenRefreshCallback,
                                       this);
   if (err != kCGErrorSuccess) {
     LOG(ERROR) << "CGRegisterScreenRefreshCallback " << err;
     return false;
   }
@@ skipping 377 matching lines @@
 Capturer* Capturer::Create() {
   CapturerMac* capturer = new CapturerMac();
   if (!capturer->Init()) {
     delete capturer;
     capturer = NULL;
   }
   return capturer;
 }
 
 }  // namespace remoting