Move Extension into extensions namespace

BUG=117262
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Review URL: https://chromiumcodereview.appspot.com/10375021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@138074 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/ui/cocoa/browser_window_cocoa.mm b/chrome/browser/ui/cocoa/browser_window_cocoa.mm
index 4e01a62..c0bf3ce 100644
--- a/chrome/browser/ui/cocoa/browser_window_cocoa.mm
+++ b/chrome/browser/ui/cocoa/browser_window_cocoa.mm
@@ -547,7 +547,7 @@
 }
 
 void BrowserWindowCocoa::ShowCreateChromeAppShortcutsDialog(
-    Profile* profile, const Extension* app) {
+    Profile* profile, const extensions::Extension* app) {
   NOTIMPLEMENTED();
 }