Implement WebContents.downloadImage() on Java side

content/public/android/java/src/org/chromium/content_public/browser/ImageDownloadCallback.java

Index: content/public/android/java/src/org/chromium/content_public/browser/ImageDownloadCallback.java
diff --git a/content/public/android/java/src/org/chromium/content_public/browser/ImageDownloadCallback.java b/content/public/android/java/src/org/chromium/content_public/browser/ImageDownloadCallback.java
new file mode 100644
index 0000000000000000000000000000000000000000..7638273ac93889f0595b02ab781979e928d9aa10
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content_public/browser/ImageDownloadCallback.java
@@ -0,0 +1,29 @@
+// 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.content_public.browser;
+
+import android.graphics.Bitmap;
+import android.graphics.Rect;
+
+import java.util.List;
+
+/**
+ * Java counterpart of native ImageDownloadCallback.
+ */
+public interface ImageDownloadCallback {
+    /**
+     * Called when image downloading is completed.
+     * @param id The unique id for the download image request, which corresponds to the return value
+     *                 of {@link WebContents.DownloadImage}.
+     * @param httpStatusCode The HTTP status code for the download request.
+     * @param imageUrl The URL of the downloaded image.
+     * @param bitmaps The bitmaps from the download image. Note that the bitmaps in the image could
+     *                 be ignored or resized if they are larger than the size limit in {@link
+     *                 WebContente.DownloadImage}.
+     * @param originalImageSizes The original sizes of {@link bitmaps} prior to the resizing.
+     */
+    void onFinishDownloadImage(int id, int httpStatusCode, String imageUrl, List<Bitmap> bitmaps,
+            List<Rect> originalImageSizes);
+}