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
new file mode 100644
index 0000000000000000000000000000000000000000..63486583c553bb5ef9c6e41c3f80758dee724c44
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/engagement/SiteEngagementService.java
@@ -0,0 +1,65 @@
+// 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) {

[gone, 2016/12/07 21:50:25]

Does this always create a new SiteEngagementService that wraps a potentially
existing native one?

[dominickn, 2016/12/08 01:03:53]

Hmm, there's an issue here with multiple ones on the Java side wrapping one on
the native side. Fixed.

+        assert ThreadUtils.runningOnUiThread();
+        return new SiteEngagementService(profile);
+    }
+
+    /**
+     * Returns the engagement score for the provided URL.
+     * Must be called on the UI thread.
+     */
+    public double getScore(String url) {
+        assert mNativePointer != 0;

[gone, 2016/12/07 21:50:25]

Not sure how useful this assert is; if the pointer is null then the native call
will crash anyway.  It might make more sense to just return early if the pointer
is 0 (for whatever potentially asynchronous reason).

[dominickn, 2016/12/08 01:03:53]

Done.

+        assert ThreadUtils.runningOnUiThread();
+        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) {
+        assert mNativePointer != 0;

[gone, 2016/12/07 21:50:25]

Ditto.

[dominickn, 2016/12/08 01:03:54]

Done.

+        assert ThreadUtils.runningOnUiThread();
+        nativeResetScoreForURL(mNativePointer, url, score);
+    }
+
+    private SiteEngagementService(Profile profile) {
+        mNativePointer = nativeGetForProfile(profile);
+    }
+
+    @CalledByNative
+    private void onNativeDestroyed() {
+        mNativePointer = 0;
+    }
+
+    private native long nativeGetForProfile(Profile profile);
+    private native double nativeGetScore(long nativeSiteEngagementServiceAndroid, String url);
+    private native void nativeResetScoreForURL(
+            long nativeSiteEngagementServiceAndroid, String url, double score);
+}