Fix a bug where an extension's icon was not being properly updated.

chrome/common/extensions/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 "chrome/common/extensions/extension.h"
 
 #include "base/base64.h"
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 150 matching lines @@
   }
 
   scoped_refptr<Extension> extension = new Extension(path, manifest.Pass());
   extension->install_warnings_.swap(install_warnings);
 
   if (!extension->InitFromValue(flags, &error)) {
     *utf8_error = UTF16ToUTF8(error);
     return NULL;
   }
 
+  extension->image_id_ = rand();
+
   return extension;
 }
 
 // static
 bool Extension::IdIsValid(const std::string& id) {
   // Verify that the id is legal.
   if (id.size() != (id_util::kIdSize * 2))
     return false;
 
   // We only support lowercase IDs, because IDs can be used as URL components
@@ skipping 661 matching lines @@
 
 UpdatedExtensionPermissionsInfo::UpdatedExtensionPermissionsInfo(
     const Extension* extension,
     const PermissionSet* permissions,
     Reason reason)
     : reason(reason),
       extension(extension),
       permissions(permissions) {}
 
 }   // namespace extensions