[Mac] Support option-return to open in new foreground tab....

chrome/browser/autocomplete/autocomplete_edit_view_mac.mm

 // Copyright (c) 2009 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 "chrome/browser/autocomplete/autocomplete_edit_view_mac.h"
 
 #include <Carbon/Carbon.h>  // kVK_Return
 #include "app/gfx/font.h"
 #include "app/l10n_util_mac.h"
 #include "app/resource_bundle.h"
@@ skipping 786 matching lines @@
   // behavior with the proper WindowOpenDisposition.
   NSEvent* event = [NSApp currentEvent];
   if (cmd == @selector(insertNewline:) ||
      (cmd == @selector(noop:) && [event keyCode] == kVK_Return)) {
     WindowOpenDisposition disposition =
         event_utils::WindowOpenDispositionFromNSEvent(event);
     edit_view_->AcceptInput(disposition, false);
     return YES;
   }
 
-  // TODO(shess): Option-return, would normally insert a literal
-  // newline.  Consider combining with -insertNewline:.
+  // Option-Return
   if (cmd == @selector(insertNewlineIgnoringFieldEditor:)) {
+    edit_view_->AcceptInput(NEW_FOREGROUND_TAB, false);
     return YES;
   }
 
   // When the user does Control-Enter, the existing content has "www."
   // prepended and ".com" appended.  |model_| should already have
   // received notification when the Control key was depressed, but it
   // is safe to tell it twice.
   if (cmd == @selector(insertLineBreak:)) {
     edit_view_->OnControlKeyChanged(true);
     WindowOpenDisposition disposition =
@@ skipping 45 matching lines @@
   // TODO(shess): Figure out where the selection belongs.  On GTK,
   // it's set to the start of the text.
 }
 
 // Signal that we've lost focus when the window resigns key.
 - (void)windowDidResignKey:(NSNotification*)notification {
   edit_view_->OnDidResignKey();
 }
 
 @end