Special case the gallery to not show the scary download roadblock.

chrome/common/extensions/extension_constants.h

 // Copyright (c) 2009 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_
 
 // Keys used in JSON representation of extensions.
 namespace extension_manifest_keys {
   extern const wchar_t* kBackground;
@@ skipping 112 matching lines @@
   extern const char* kInvalidUpdateURL;
   extern const char* kInvalidDefaultLocale;
   extern const char* kLocalesNoDefaultLocaleSpecified;
   extern const char* kLocalesNoDefaultMessages;
   extern const char* kLocalesNoValidLocaleNamesListed;
   extern const char* kLocalesTreeMissing;
   extern const char* kLocalesMessagesFileMissing;
   extern const char* kInvalidOptionsPage;
 }  // namespace extension_manifest_errors
 
+namespace extension_urls {
+  // The greatest common prefixes of the main extensions gallery's browse and
+  // download URLs.
+  extern const char* kGalleryBrowsePrefix;
+  extern const char* kGalleryDownloadPrefix;
+
+  // Same thing for the "minigallery". The minigallery is the temporary static
+  // themes gallery that we put up when we launched themes.
+  extern const char* kMiniGalleryBrowsePrefix;
+  extern const char* kMiniGalleryDownloadPrefix;
+}  // namespace extension_urls
+
 #endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_