Make --disable-gpu-vsync work with CoreAnimation

content/browser/renderer_host/compositing_iosurface_context_mac.mm

Index: content/browser/renderer_host/compositing_iosurface_context_mac.mm
diff --git a/content/browser/renderer_host/compositing_iosurface_context_mac.mm b/content/browser/renderer_host/compositing_iosurface_context_mac.mm
index 2daef5de9b3ff5f339d6bb9cb42451d2c581a6c8..899703bdf42223f3f8714a80f7ae33b6d20a64d0 100644
--- a/content/browser/renderer_host/compositing_iosurface_context_mac.mm
+++ b/content/browser/renderer_host/compositing_iosurface_context_mac.mm
@@ -144,10 +144,13 @@ CompositingIOSurfaceContext::Get(int window_number) {
     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(