Expose the Site Engagement Service to Java.

chrome/android/java/src/org/chromium/chrome/browser/engagement/SiteEngagementService.java

Index: chrome/android/java/src/org/chromium/chrome/browser/engagement/SiteEngagementService.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/engagement/SiteEngagementService.java b/chrome/android/java/src/org/chromium/chrome/browser/engagement/SiteEngagementService.java
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index 0000000000000000000000000000000000000000..316aa147e7f95db1617439e2ab57cfa3a1a66bca
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/engagement/SiteEngagementService.java
@@ -0,0 +1,72 @@
+// 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.
+
+package org.chromium.chrome.browser.engagement;
+
+import org.chromium.base.ThreadUtils;
+import org.chromium.base.annotations.CalledByNative;
+
+import org.chromium.chrome.browser.profiles.Profile;
+
+/**
+ * Provides access to the Site Engagement Service for a profile.
+ *
+ * Site engagement measures the level of engagement that a user has with an origin. This class
+ * allows Java to retrieve and modify engagement scores for URLs.
+ */
+public class SiteEngagementService {
+
+    /** Pointer to the native side SiteEngagementServiceAndroid shim. */
+    private long mNativePointer;
+
+    /**
+     * Returns a SiteEngagementService for the provided profile.
+     * Must be called on the UI thread.
+     */
+    public static SiteEngagementService getForProfile(Profile profile) {
+        assert ThreadUtils.runningOnUiThread();
+        return nativeSiteEngagementServiceForProfile(profile);
+    }
+
+    /**
+     * Returns the engagement score for the provided URL.
+     * Must be called on the UI thread.
+     */
+    public double getScore(String url) {
+        assert ThreadUtils.runningOnUiThread();
+        if (mNativePointer == 0) return 0.0;
+        return nativeGetScore(mNativePointer, url);
+    }
+
+    /**
+     * Sets the provided URL to have the provided engagement score.
+     * Must be called on the UI thread.
+     */
+    public void resetScoreForUrl(String url, double score) {

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

Nit: can you put ..ForTest on this, and on the corresponding native function? I
assume we'd only ever want to do this in a test.

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

No, this native method is used by the chrome://site-engagement page handler to
reset scores when edited by users. It's not just used for tests.

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

Acknowledged.

+        assert ThreadUtils.runningOnUiThread();
+        if (mNativePointer == 0) return;
+        nativeResetScoreForURL(mNativePointer, url, score);
+    }
+
+    @CalledByNative
+    private static SiteEngagementService create(long nativePointer) {
+        return new SiteEngagementService(nativePointer);
+    }
+
+    /** This object may only be created via the static getForProfile method. */

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

Is this used? getForProfile doesn't call this.

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

This method is called by create(), which is called across the JNI by
SiteEngagementServiceAndroid to make one of these things.

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

Acknowledged.

+    private SiteEngagementService(long nativePointer) {
+        mNativePointer = nativePointer;
+    }
+
+    @CalledByNative
+    private void onNativeDestroyed() {
+        mNativePointer = 0;
+    }
+
+    private static native SiteEngagementService nativeSiteEngagementServiceForProfile(
+            Profile profile);
+    private native double nativeGetScore(long nativeSiteEngagementServiceAndroid, String url);
+    private native void nativeResetScoreForURL(
+            long nativeSiteEngagementServiceAndroid, String url, double score);
+}