Expose the Site Engagement Service to Java.

chrome/browser/engagement/site_engagement_service_android.cc

+// 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.
+
+#include "chrome/browser/engagement/site_engagement_service_android.h"
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_string.h"
+#include "base/memory/ptr_util.h"
+#include "chrome/browser/profiles/profile_android.h"
+#include "jni/SiteEngagementService_jni.h"
+#include "url/gurl.h"
+
+using base::android::JavaParamRef;
+
+// static
+bool SiteEngagementServiceAndroid::Register(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+// static
+const base::android::ScopedJavaGlobalRef<jobject>&
+SiteEngagementServiceAndroid::GetOrCreate(JNIEnv* env,
+                                          SiteEngagementService* service) {
+  SiteEngagementServiceAndroid* android_service = service->GetAndroidService();
+  if (!android_service) {
+    service->SetAndroidService(
+        base::MakeUnique<SiteEngagementServiceAndroid>(env, service));
+    android_service = service->GetAndroidService();
+  }
+
+  return android_service->java_service_;
+}
+
+SiteEngagementServiceAndroid::SiteEngagementServiceAndroid(
+    JNIEnv* env,
+    SiteEngagementService* service)
+    : service_(service) {
+  java_service_.Reset(Java_SiteEngagementService_create(
+      env, reinterpret_cast<uintptr_t>(this)));
+}
+
+SiteEngagementServiceAndroid::~SiteEngagementServiceAndroid() {
+  Java_SiteEngagementService_onNativeDestroyed(
+      base::android::AttachCurrentThread(), java_service_);
+  java_service_.Reset();
+}
+
+double SiteEngagementServiceAndroid::GetScore(
+    JNIEnv* env,
+    const JavaParamRef<jobject>& caller,
+    const JavaParamRef<jstring>& jurl) const {
+  if (!jurl)
+    return 0;
+
+  return service_->GetScore(
+      GURL(base::android::ConvertJavaStringToUTF16(env, jurl)));
+}
+
+void SiteEngagementServiceAndroid::ResetScoreForURL(
+    JNIEnv* env,
+    const JavaParamRef<jobject>& caller,
+    const JavaParamRef<jstring>& jurl,
+    double score) {
+  if (jurl) {
+    service_->ResetScoreForURL(
+        GURL(base::android::ConvertJavaStringToUTF16(env, jurl)), score);
+  }
+}
+
+base::android::ScopedJavaLocalRef<jobject> SiteEngagementServiceForProfile(

[benwells, 2016/12/09 04:31:32]

Out of interest, how does this get hooked up to
nativeSiteEngagementServiceForProfile? Is it pure magic?

[dominickn, 2016/12/09 04:44:17]

The JNI bindings generator generates the declaration for this method (by slicing
native off nativeSiteEngagementServiceForProfile and interpolating the arguments
from Java, e.g. a class static method or an object non-static method) and calls
it, sending the LocalRef it returns to Java as a SiteEngagementService Java-side
object.

[benwells, 2016/12/09 04:57:36]

Cool, thanks for the explanation!

+    JNIEnv* env,
+    const JavaParamRef<jclass>& clazz,
+    const JavaParamRef<jobject>& jprofile) {
+  Profile* profile = ProfileAndroid::FromProfileAndroid(jprofile);
+  SiteEngagementService* service = SiteEngagementService::Get(profile);
+  DCHECK(service);
+
+  return base::android::ScopedJavaLocalRef<jobject>(
+      SiteEngagementServiceAndroid::GetOrCreate(env, service));
+}