Add BlimpClientContext and factory with real and dummy implementation

blimp/client/app/android/blimp_jni_registrar.h

-// Copyright 2015 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 BLIMP_CLIENT_APP_ANDROID_BLIMP_JNI_REGISTRAR_H_
-#define BLIMP_CLIENT_APP_ANDROID_BLIMP_JNI_REGISTRAR_H_
-
-#include <jni.h>
-
-namespace blimp {
-namespace client {
-
-// Registers native method hooks with the Java runtime specified by |env|.
-// Returns false if registration fails, in which case native methods are
-// unavailable to Java.
-bool RegisterBlimpJni(JNIEnv* env);
-
-}  // namespace client
-}  // namespace blimp
-
-#endif  // BLIMP_CLIENT_APP_ANDROID_BLIMP_JNI_REGISTRAR_H_