Move content settings extension API to content_settings dir.

chrome/browser/extensions/api/content_settings/content_settings_api_constants.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 "chrome/browser/extensions/extension_content_settings_api_constants.h"
+#include "chrome/browser/extensions/api/content_settings/content_settings_api_constants.h"
 
-namespace extension_content_settings_api_constants {
+namespace extensions {
+namespace content_settings_api_constants {
 
 // Keys.
 const char kContentSettingKey[] = "setting";
 const char kContentSettingsTypeKey[] = "type";
 const char kDescriptionKey[] = "description";
 const char kIdKey[] = "id";
 const char kPatternKey[] = "pattern";
 const char kPrimaryPatternKey[] = "primaryPattern";
 const char kPrimaryUrlKey[] = "primaryUrl";
 const char kResourceIdentifierKey[] = "resourceIdentifier";
 const char kRuleKey[] = "rule";
 const char kSecondaryPatternKey[] = "secondaryPattern";
 const char kSecondaryUrlKey[] = "secondaryUrl";
 
 // Errors.
 const char kIncognitoContextError[] =
     "Can't modify regular settings from an incognito context.";
 const char kIncognitoSessionOnlyError[] =
     "You cannot read incognito content settings when no incognito window "
     "is open.";
 const char kInvalidUrlError[] = "The URL \"*\" is invalid.";
 
-}  // extension_content_settings_api_constants
+}  // namespace content_settings_api_constants
+}  // namespace extensions