Fix "Get more extensions" link in about:extensions.

chrome/common/extensions/extension_constants.h

Index: chrome/common/extensions/extension_constants.h
diff --git a/chrome/common/extensions/extension_constants.h b/chrome/common/extensions/extension_constants.h
index 1a952418dd5c12a4178e7889b00dc40b2ffe336f..ef23a7761b2316e5de195b97798b57c49be3fae6 100644
--- a/chrome/common/extensions/extension_constants.h
+++ b/chrome/common/extensions/extension_constants.h
@@ -16,6 +16,10 @@ namespace extension_urls {
   // slash. Do not use this as a prefix/extent for the store.
   std::string GetWebstoreLaunchURL();
 
+  // Returns the URL to the extensions category on the Web Store. This is
+  // derived from GetWebstoreLaunchURL().
+  std::string GetExtensionGalleryURL();
+
   // Returns the URL prefix for an item in the extension/app gallery. This URL
   // will contain a trailing slash and should be concatenated with an item ID
   // to get the item detail URL.