Add the JNI code in order to let Java use the InterestsFetcher.

chrome/browser/android/interests_service.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 CHROME_BROWSER_ANDROID_INTERESTS_SERVICE_H_
+#define CHROME_BROWSER_ANDROID_INTERESTS_SERVICE_H_
+
+#include <jni.h>
+
+#include "base/android/scoped_java_ref.h"
+#include "chrome/browser/interests/interests_fetcher.h"
+#include "chrome/browser/profiles/profile.h"
+
+// Provides a list of user interests to Java
+class InterestsService {
+ public:
+  explicit InterestsService(Profile* profile);
+  void Destroy(JNIEnv* env, jobject obj);

[Bernhard Bauer, 2015/09/29 14:04:05]

I would group methods that are called from Java together and add a comment
before the group starts.

[PEConn, 2015/10/07 13:55:21]

Done.

+
+  void GetInterests(JNIEnv* env,
+                    jobject obj,
+                    jobject j_callback);
+
+  static jobjectArray ConvertInterestsToJava(
+      const std::vector<InterestsFetcher::Interest>& interests);
+
+  static bool Register(JNIEnv* env);
+  virtual ~InterestsService();

[Bernhard Bauer, 2015/09/29 14:04:05]

Destructors should come before other methods.

[PEConn, 2015/10/07 13:55:21]

Done.

+
+ private:
+  void OnObtainedInterests(
+      InterestsFetcher* fetcher,
+      scoped_ptr<base::android::ScopedJavaGlobalRef<jobject>> j_callback,
+      const std::vector<InterestsFetcher::Interest>& interests);
+
+  Profile* profile_;
+
+  base::WeakPtrFactory<InterestsService> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(InterestsService);
+};
+
+#endif  // CHROME_BROWSER_ANDROID_INTERESTS_SERVICE_H_