[AiS] Java bridge for AnswersImageService

chrome/android/java/src/org/chromium/chrome/browser/omnibox/AnswersImage.java

Index: chrome/android/java/src/org/chromium/chrome/browser/omnibox/AnswersImage.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/omnibox/AnswersImage.java b/chrome/android/java/src/org/chromium/chrome/browser/omnibox/AnswersImage.java
new file mode 100644
index 0000000000000000000000000000000000000000..2be96aa3890214f7e9540e128afc4ec27308bdf8
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/omnibox/AnswersImage.java
@@ -0,0 +1,83 @@
+// Copyright 2014 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.omnibox;
+
+import android.graphics.Bitmap;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.chrome.browser.profiles.Profile;
+
+/**
+ * Provides access to images used by Answers in Suggest.
+ */
+public class AnswersImage {
+    /**
+     * Observer for updating an image when it is available.
+     */
+    public interface AnswersImageObserver {
+        /**
+         * Called when the image is updated.
+         *
+         * @param answersImage the image
+         */
+        @CalledByNative("AnswersImageObserver")
+        public void onAnswersImageChanged(Bitmap bitmap);
+    }
+
+    /**
+     * Encapsulates requests to the AnswerImagesService.
+     */
+    public static class AnswersImageRequest {
+      public final AnswersImageObserver observer;

[Ted C, 2014/06/06 01:49:23]

the indenting of this needs to be 4 (and many places in this file are using 2
space indenting instead of 4).

[groby-ooo-7-16, 2014/06/13 23:52:21]

Done.

+      public final int requestId;
+
+      public AnswersImageRequest(AnswersImageObserver observer, int requestId) {
+        this.observer = observer;
+        this.requestId = requestId;
+      }
+    }
+
+    /**
+     * Request image, observer is notified when image is loaded.
+     * @param profile     Profile that the request is for.
+     * @param imageUrl    URL for image data.
+     * @param observer    Observer to be notified when image is updated.
+     * @return            An AnswersImageRequest.
+     */
+    public static AnswersImageRequest requestAnswersImage(

[Ted C, 2014/06/06 01:49:23]

why not just pass back the request ID here?  You passed in the observer, so it
doesn't really need to come back in the request.

[groby-ooo-7-16, 2014/06/13 23:52:21]

It allows the Java side to hold a pointer to the observer. I'd like to avoid the
C++ side holding on to Java objects, and if the observer is an anonymous class,
somebody needs to hold on to it.

[Ted C, 2014/06/17 20:38:15]

I don't agree with this.  I think it is entirely reasonable (and
consistent with how we do other c++ -> java callbacks) for C++ to
own a strong reference to this callback while it is pending a
response.

Personally, I think this API is actually more confusing and error
prone as it allows you to create an anonymous callback, but if you
didn't infer that you needed to hold onto the request return value
then it would be GC'd underneath.  And if you didn't care to ever
cancel your pending callback, then there is no need to actually
keep a reference.

I think changing native to hold a scoped strong global ref makes
this simpler on all sides of the api boundary.

[groby-ooo-7-16, 2014/06/17 23:46:20]

So be it. We'll see what shakes out of the ownership tree ;)

+        Profile profile, String imageUrl, AnswersImageObserver observer) {
+      return nativeRequestAnswersImage(profile, imageUrl, observer);
+    }
+
+    /**
+     * Cancel a pending image request.
+     * @param profile    Profile the request was issued for.
+     * @param requestId  The ID of the request to be cancelled.
+     */
+    public static void cancelAnswersImageRequest(Profile profile, int requestId) {
+      nativeCancelAnswersImageRequest(profile, requestId);
+    }
+
+    /**
+     * Allows the native side to generate AnswersImageRequest objects.
+     */
+    @CalledByNative
+    private static AnswersImageRequest createAnswersImageRequest(
+        AnswersImageObserver observer, int requestId) {
+      return new AnswersImageRequest(observer, requestId);
+    }
+
+    /**
+     * Requests an image at |imageUrl| for the given |profile| with |observer| being notified.
+     * @returns an AnswersImageRequest
+     */
+    private static native AnswersImageRequest nativeRequestAnswersImage(
+        Profile profile, String imageUrl, AnswersImageObserver observer);
+
+    /**
+     * Cancels a pending request.
+     */
+    private static native void nativeCancelAnswersImageRequest(Profile profile, int requestId);
+}