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..c02176dda4e05a3db8ed8d2cf699902f2d318efa
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content_public/browser/ImageDownloadCallback.java
@@ -0,0 +1,21 @@
+// 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.
+     */
+    void onFinishDownloadImage(int id, int httpStatusCode, String imageUrl, List<Bitmap> bitmaps,

[Ted C, 2016/06/03 16:44:09]

Might be good to add javadoc about these.

In particular, sizes is somewhat unexpected as it reflect the original size
prior to resizing.

[Zhiqiang Zhang (Slow), 2016/06/03 18:53:51]

Done.

+                               List<Rect> sizes);

[Ted C, 2016/06/03 16:44:09]

same indenting comment (here and the following files)

[Zhiqiang Zhang (Slow), 2016/06/03 18:53:52]

Done.

+}