Move ExtensionHost into extensions namespace

chrome/browser/extensions/extension_host_mac.mm

Index: chrome/browser/extensions/extension_host_mac.mm
diff --git a/chrome/browser/extensions/extension_host_mac.mm b/chrome/browser/extensions/extension_host_mac.mm
index c3096d100b2d3a41cf8f3cc4847e2c9cf88ee2d7..bf862b7bff049adb2e030c7f0a2e778cec175a13 100644
--- a/chrome/browser/extensions/extension_host_mac.mm
+++ b/chrome/browser/extensions/extension_host_mac.mm
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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.
 
@@ -12,6 +12,8 @@
 
 using content::NativeWebKeyboardEvent;
 
+namespace extensions {
+
 ExtensionHostMac::~ExtensionHostMac() {
   // If there is a popup open for this host's extension, close it.
   ExtensionPopupController* popup = [ExtensionPopupController popup];
@@ -35,3 +37,5 @@ void ExtensionHostMac::UnhandledKeyboardEvent(
   DCHECK([event_window isKindOfClass:[ChromeEventProcessingWindow class]]);
   [event_window redispatchKeyEvent:event.os_event];
 }
+
+}  // namespace extensions