Move PageTransition into content namespace. While I'm touching all these files, I've also updated...

chrome/browser/ui/gtk/extensions/extension_install_dialog_gtk.cc

 // Copyright (c) 2011 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 <gtk/gtk.h>
 
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/extensions/extension_install_dialog.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 208 matching lines @@
   }
 
   gtk_widget_destroy(dialog_);
   delete this;
 }
 
 void ExtensionInstallDialog::OnStoreLinkClick(GtkWidget* sender) {
   GURL store_url(
       extension_urls::GetWebstoreItemDetailURLPrefix() + extension_->id());
   BrowserList::GetLastActive()->OpenURL(OpenURLParams(
-      store_url, GURL(), NEW_FOREGROUND_TAB, PageTransition::LINK));
+      store_url, GURL(), NEW_FOREGROUND_TAB, content::PAGE_TRANSITION_LINK));
 
   OnResponse(dialog_, GTK_RESPONSE_CLOSE);
 }
 
 }  // namespace
 
 void ShowExtensionInstallDialog(
     Profile* profile,
     ExtensionInstallUI::Delegate* delegate,
     const Extension* extension,
@@ skipping 11 matching lines @@
     delegate->InstallUIAbort(false);
     return;
   }
 
   new ExtensionInstallDialog(browser_window->window(),
                              delegate,
                              extension,
                              icon,
                              prompt);
 }