Make --disable-gpu-vsync work with CoreAnimation

content/browser/renderer_host/compositing_iosurface_context_mac.mm

 // Copyright (c) 2013 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/compositing_iosurface_context_mac.h"
 
 #include <OpenGL/gl.h>
 #include <OpenGL/OpenGL.h>
 #include <vector>
 
@@ skipping 126 matching lines @@
           shader_program_cache->UseBlitProgram() &&
           shader_program_cache->UseSolidWhiteProgram());
     }
     glUseProgram(0u);
   }
   if (!prepared) {
     LOG(ERROR) << "IOSurface failed to compile/link required shader programs.";
     return NULL;
   }
 
-  scoped_refptr<DisplayLinkMac> display_link = DisplayLinkMac::Create();
-  if (!display_link) {
-    LOG(ERROR) << "Failed to create display link for GL context.";
-    return NULL;
+  scoped_refptr<DisplayLinkMac> display_link;
+  if (!is_vsync_disabled) {
+    display_link = DisplayLinkMac::Create();
+    if (!display_link) {
+      LOG(ERROR) << "Failed to create display link for GL context.";
+      return NULL;
+    }
   }
 
   return new CompositingIOSurfaceContext(
       window_number,
       nsgl_context.release(),
       cgl_context_strong,
       cgl_context,
       is_vsync_disabled,
       display_link,
       shader_program_cache.Pass());
@@ skipping 72 matching lines @@
 CompositingIOSurfaceContext::WindowMap*
     CompositingIOSurfaceContext::window_map() {
   return window_map_.Pointer();
 }
 
 // static
 base::LazyInstance<CompositingIOSurfaceContext::WindowMap>
     CompositingIOSurfaceContext::window_map_;
 
 }  // namespace content