Opt out of macOS Sierra automatic window tabbing

chrome/browser/app_controller_mac.mm

Index: chrome/browser/app_controller_mac.mm
diff --git a/chrome/browser/app_controller_mac.mm b/chrome/browser/app_controller_mac.mm
index f371b8bc0f65cd33997b33844cb0fff735e4260d..5c6d4e518d14375638e277344e384548d8961ced 100644
--- a/chrome/browser/app_controller_mac.mm
+++ b/chrome/browser/app_controller_mac.mm
@@ -408,6 +408,10 @@ class AppControllerProfileObserver : public ProfileAttributesStorage::Observer {
 - (void)applicationWillFinishLaunching:(NSNotification*)notification {
   MacStartupProfiler::GetInstance()->Profile(
       MacStartupProfiler::WILL_FINISH_LAUNCHING);
+
+  if ([NSWindow respondsToSelector:@selector(allowsAutomaticWindowTabbing)]) {

[Nico, 2016/09/12 14:13:58]

is checking for `setAllowsAutomaticWindowTabbing:` more correct since that's
what you're calling? (optional comment, doesn't matter in practice)

[Sidney San Martín, 2016/09/12 15:07:25]

You are technically correct — the best kind of correct.

I thought about this before I submitted. I kept it because even though
`setAllowsAutomaticWindowTabbing:` is the actual method, I feel like
`allowsAutomaticWindowTabbing` more clearly expresses our intent to make sure
the property exists at all.

+    NSWindow.allowsAutomaticWindowTabbing = NO;
+  }
 }
 
 - (void)applicationWillHide:(NSNotification*)notification {