Enforce new id format (hex str of sha-1)

Review URL: http://codereview.chromium.org/27236

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@10529 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/extensions/extension.h b/chrome/browser/extensions/extension.h
index 39e5fff..48833d45 100644
--- a/chrome/browser/extensions/extension.h
+++ b/chrome/browser/extensions/extension.h
@@ -64,6 +64,9 @@
   static const char* kInvalidZipHashError;
   static const char* kInvalidPluginsDirError;
 
+  // The number of bytes in a legal id.
+  static const int kIdSize;
+
   // Creates an absolute url to a resource inside an extension. The
   // |extension_url| argument should be the url() from an Extension object. The
   // |relative_path| can be untrusted user input. The returned URL will either