Remove TabContents from TabStripModelObserver::TabDetachedAt.

BUG=107201
TEST=no visible change


Review URL: https://chromiumcodereview.appspot.com/11293205

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@167122 0039d316-1c4b-4281-b951-d872f2087c98
AutomationProviderBookmarkModelObserver(
    AutomationProvider* provider,
    IPC::Message* reply_message,
    BookmarkModel* model,
    bool use_json_interface)
    : automation_provider_(provider->AsWeakPtr()),
      reply_message_(reply_message),
      model_(model),
      use_json_interface_(use_json_interface) {
  model_->AddObserver(this);
}

AutomationProviderBookmarkModelObserver(
    AutomationProvider* provider,
    IPC::Message* reply_message,
    BookmarkModel* model,
    bool use_json_interface)
    : automation_provider_(provider->AsWeakPtr()),
      reply_message_(reply_message),
      model_(model),
      use_json_interface_(use_json_interface) {
  model_->AddObserver(this);
}
