Add an extension bubble explaining which extensions are in dev mode.

extensions/common/extension.cc

 // Copyright (c) 2013 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.
 
 #include "extensions/common/extension.h"
 
 #include "base/base64.h"
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 368 matching lines @@
   if (Manifest::IsUnpackedLocation(location()))
     return false;
 
   // Don't show apps that aren't visible in either launcher or ntp.
   if (is_app() && !ShouldDisplayInAppLauncher() && !ShouldDisplayInNewTabPage())
     return true;
 
   return false;
 }
 
+bool Extension::IsDevModeExtension() const {
+  return location() == Manifest::UNPACKED ||
+         location() == Manifest::COMMAND_LINE;
+}
+
 Extension::ManifestData* Extension::GetManifestData(const std::string& key)
     const {
   DCHECK(finished_parsing_manifest_ || thread_checker_.CalledOnValidThread());
   ManifestDataMap::const_iterator iter = manifest_data_.find(key);
   if (iter != manifest_data_.end())
     return iter->second.get();
   return NULL;
 }
 
 void Extension::SetManifestData(const std::string& key,
@@ skipping 385 matching lines @@
 
 UpdatedExtensionPermissionsInfo::UpdatedExtensionPermissionsInfo(
     const Extension* extension,
     const PermissionSet* permissions,
     Reason reason)
     : reason(reason),
       extension(extension),
       permissions(permissions) {}
 
 }   // namespace extensions