[unpacker] Install the new zip unpacker extension by default.

chrome/common/extensions/extension_constants.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_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_
 #define CHROME_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 212 matching lines @@
 extern const char kConnectivityDiagnosticsKioskPath[];
 extern const char kConnectivityDiagnosticsLauncherPath[];
 // Path to preinstalled speech synthesis extension.
 extern const char kSpeechSynthesisExtensionPath[];
 // The extension id of the speech synthesis extension.
 extern const char kSpeechSynthesisExtensionId[];
 // The extension id of the wallpaper manager application.
 extern const char kWallpaperManagerId[];
 // The extension id of the first run dialog application.
 extern const char kFirstRunDialogId[];
+// The extension id of the new ZIP unpacker extension.
+extern const char kZIPUnpackerExtensionId[];
 #endif
 
 // What causes an extension to be installed? Used in histograms, so don't
 // change existing values.
 enum CrxInstallCause {
   INSTALL_CAUSE_UNSET = 0,
   INSTALL_CAUSE_USER_DOWNLOAD,
   INSTALL_CAUSE_UPDATE,
   INSTALL_CAUSE_EXTERNAL_FILE,
   INSTALL_CAUSE_AUTOMATION,
@@ skipping 46 matching lines @@
   LAUNCH_CONTAINER_PANEL,
   LAUNCH_CONTAINER_TAB,
   // For platform apps, which don't actually have a container (they just get a
   // "onLaunched" event).
   LAUNCH_CONTAINER_NONE
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_