WebAPKs: Fix play-install variations check

chrome/browser/android/webapk/chrome_webapk_host.h

 // Copyright 2016 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.
 
 #ifndef CHROME_BROWSER_ANDROID_WEBAPK_CHROME_WEBAPK_HOST_H_
 #define CHROME_BROWSER_ANDROID_WEBAPK_CHROME_WEBAPK_HOST_H_
 
+#include <jni.h>
+
 #include "base/macros.h"
 
 // ChromeWebApkHost is the C++ counterpart of org.chromium.chrome.browser's
 // ChromeWebApkHost in Java.
 class ChromeWebApkHost {
  public:
+  // Registers JNI hooks.
+  static bool Register(JNIEnv* env);
+
   // Returns whether the "enalbe-webapk" is turned on.
   static bool AreWebApkEnabled();
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ChromeWebApkHost);
 };
 
 #endif  // CHROME_BROWSER_ANDROID_WEBAPK_CHROME_WEBAPK_HOST_H_