In android_webview/browser/aw_contents.cc:

class AwContentsUserData : public base::SupportsUserData::Data {
 public:
  explicit AwContentsUserData(AwContents* ptr) : contents_(ptr) {}

  static AwContents* GetContents(WebContents* web_contents) {
    if (!web_contents)
      return NULL;
    AwContentsUserData* data = static_cast<AwContentsUserData*>(
        web_contents->GetUserData(kAwContentsUserDataKey));
    return data ? data->contents_ : NULL;
  }

 private:
  AwContents* contents_;
};

contents_ (actually, the whole AwContentsUserData class) seems unnecessary since https://codereview.chromium.org/10941015. Or am I reading this wrong?