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

chrome/browser/android/interests_service.cc

+// 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.
+
+#include "chrome/browser/android/interests_service.h"
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_array.h"
+#include "base/android/jni_string.h"
+#include "base/android/scoped_java_ref.h"
+#include "base/callback.h"
+#include "base/command_line.h"

[Marc Treib, 2015/09/11 14:54:25]

Not needed, also the next three (and probably some more)

[tache, 2015/09/11 15:45:09]

Done.

+#include "base/compiler_specific.h"
+#include "base/metrics/histogram.h"
+#include "base/metrics/sparse_histogram.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/stringprintf.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/time/time.h"
+#include "chrome/browser/interests/interests_fetcher.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/profiles/profile_android.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/url_data_source.h"
+#include "jni/InterestsService_jni.h"
+#include "url/gurl.h"
+
+using base::android::AttachCurrentThread;
+using base::android::ConvertJavaStringToUTF8;
+using base::android::ScopedJavaGlobalRef;
+using base::android::ScopedJavaLocalRef;
+using base::android::ToJavaArrayOfStrings;
+
+namespace {
+
+const char kInterestJavaClass[] =
+    "org/chromium/chrome/browser/ntp/InterestsService$Interest";
+
+} // end namespace
+
+
+InterestsService::InterestsService(Profile *profile):
+  profile_(profile), weak_ptr_factory_(this) {
+}
+
+InterestsService::~InterestsService() {
+}
+
+void InterestsService::Destroy(JNIEnv* env, jobject obj) {
+  delete this;
+}
+
+
+
+void InterestsService::GetInterests(JNIEnv* env,
+                             jobject obj,
+                             jstring j_token,
+                             jobject j_callback_obj) {
+  scoped_ptr<ScopedJavaGlobalRef<jobject>> j_callback(
+      new ScopedJavaGlobalRef<jobject>());
+
+  j_callback->Reset(env, j_callback_obj);
+  std::string token = ConvertJavaStringToUTF8(env, j_token);
+
+  InterestsFetcher* fetcher =
+      new InterestsFetcher(profile_->GetRequestContext(),
+                         token);
+
+  InterestsFetcher::InterestsCallback callback =
+      base::Bind(&InterestsService::OnObtainedInterests,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 fetcher,

[Marc Treib, 2015/09/11 14:54:25]

Can you use base::Owned here? Then |fetcher| should be deleted automatically
after the callback has run.
(Raw pointers are generally taken to mean "non-owning" in Chromium. For an
owning pointer, you should generally use scoped_ptr.)

[tache, 2015/09/11 15:45:09]

Done.

+                 base::Passed(&j_callback));
+
+  fetcher->Start(callback);
+}
+
+// static
+bool InterestsService::Register(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+
+jobjectArray InterestsService::ConvertInterestsToJava(
+    const std::vector<InterestsFetcher::Interest>& interests) {
+  JNIEnv* env = AttachCurrentThread();
+  jclass interest_class = env->FindClass(kInterestJavaClass);
+
+  jobjectArray j_interests =
+      env->NewObjectArray(interests.size(), interest_class, 0);
+
+  for (uint i = 0; i != interests.size(); i++) {

[Marc Treib, 2015/09/11 14:54:25]

nit: size_t

[tache, 2015/09/11 15:45:09]

Done.

+    ScopedJavaLocalRef<jobject> j_interest =
+        Java_InterestsService_createInterest(env,
+            env->NewStringUTF(interests[i].name.c_str()),
+            env->NewStringUTF(interests[i].image_url.c_str()),
+            interests[i].relevance);
+
+    env->SetObjectArrayElement(j_interests, i, j_interest.obj());
+  }
+
+  return j_interests;
+}
+
+void InterestsService::OnObtainedInterests(
+    InterestsFetcher* fetcher,
+    scoped_ptr<ScopedJavaGlobalRef<jobject>> j_callback,
+    const std::vector<InterestsFetcher::Interest>& interests) {
+  JNIEnv* env = AttachCurrentThread();
+
+  jobjectArray j_interests =
+      InterestsService::ConvertInterestsToJava(interests);
+
+  Java_GetInterestsCallback_onInterestsCallback(
+      env, j_callback->obj(), j_interests);
+
+  base::MessageLoop::current()->DeleteSoon(FROM_HERE, fetcher);
+}
+
+static jlong Init(JNIEnv* env,
+                  const JavaParamRef<jobject>& jobj,
+                  const JavaParamRef<jobject>& jprofile) {
+  InterestsService *interests_service = new InterestsService(
+      ProfileAndroid::FromProfileAndroid(jprofile));
+  return reinterpret_cast<intptr_t>(interests_service);
+}