Convert WindowOpenDisposition to an enum class.

chrome/browser/ui/cocoa/extensions/extension_install_view_controller.mm

 // Copyright (c) 2012 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.
 
 #import "chrome/browser/ui/cocoa/extensions/extension_install_view_controller.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 234 matching lines @@
     delegate_ = delegate;
     prompt_ = std::move(prompt);
     warnings_.reset([[self buildWarnings:*prompt_] retain]);
   }
   return self;
 }
 
 - (IBAction)storeLinkClicked:(id)sender {
   GURL store_url(extension_urls::GetWebstoreItemDetailURLPrefix() +
                  prompt_->extension()->id());
-  OpenURLParams params(store_url, Referrer(), NEW_FOREGROUND_TAB,
-      ui::PAGE_TRANSITION_LINK, false);
+  OpenURLParams params(store_url, Referrer(),
+                       WindowOpenDisposition::NEW_FOREGROUND_TAB,
+                       ui::PAGE_TRANSITION_LINK, false);
   if (navigator_) {
     navigator_->OpenURL(params);
   } else {
     chrome::ScopedTabbedBrowserDisplayer displayer(profile_);
     displayer.browser()->OpenURL(params);
   }
 
   delegate_->OnStoreLinkClicked();
 }
 
@@ skipping 570 matching lines @@
 }
 
 - (void)accessibilityPerformAction:(NSString*)action {
   if ([action isEqualToString:NSAccessibilityPressAction])
     [self handleLinkClicked];
   else
     [super accessibilityPerformAction:action];
 }
 
 @end