Update references to the extension messaging APIs to point to the "runtime"

chrome/browser/extensions/api/downloads/downloads_api.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_DOWNLOADS_DOWNLOADS_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_DOWNLOADS_DOWNLOADS_API_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 15 matching lines @@
 class ResourceContext;
 class ResourceDispatcherHost;
 }
 
 // Functions in the chrome.downloads namespace facilitate
 // controlling downloads from extensions. See the full API doc at
 // http://goo.gl/6hO1n
 
 namespace download_extension_errors {
 
-// Errors that can be returned through chrome.extension.lastError.message.
+// Errors that can be returned through chrome.runtime.lastError.message.
 extern const char kGenericError[];
 extern const char kIconNotFoundError[];
 extern const char kInvalidDangerTypeError[];
 extern const char kInvalidFilterError[];
 extern const char kInvalidOperationError[];
 extern const char kInvalidOrderByError[];
 extern const char kInvalidQueryLimit[];
 extern const char kInvalidStateError[];
 extern const char kInvalidURLError[];
 extern const char kNotImplementedError[];
@@ skipping 192 matching lines @@
  private:
   void DispatchEvent(const char* event_name, base::Value* json_arg);
 
   Profile* profile_;
   AllDownloadItemNotifier notifier_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionDownloadsEventRouter);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_DOWNLOADS_DOWNLOADS_API_H_