Implement WebContents.downloadImage() on Java side

This CL bridges the native WebContents::DownloadImage to Java. We are planning to use the method for fetching artwork images (WIP) in MediaMetadata and show them in Android media notification.

Related CLs:
https://codereview.chromium.org/2013813002/
https://codereview.chromium.org/2015433003/
https://codereview.chromium.org/2009243002/ (most relevant one)

BUG=616411

Review-Url: https://codereview.chromium.org/2014553002
Cr-Commit-Position: refs/heads/master@{#397807}

content/browser/web_contents/web_contents_android.cc

@@ -673,6 +673,25 @@ void WebContentsAndroid::ReloadLoFiImages(JNIEnv* env,
   static_cast<WebContentsImpl*>(web_contents_)->ReloadLoFiImages();
 }
 
+int WebContentsAndroid::DownloadImage(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& obj,
+    const base::android::JavaParamRef<jstring>& jurl,
+    jboolean is_fav_icon,
+    jint max_bitmap_size,
+    jboolean bypass_cache,
+    const base::android::JavaParamRef<jobject>& jcallback) {
+  GURL url(base::android::ConvertJavaStringToUTF8(env, jurl));
+  return web_contents_->DownloadImage(
+      url, is_fav_icon, max_bitmap_size, bypass_cache,
+      base::Bind(&WebContentsAndroid::OnFinishDownloadImage,
+                 weak_factory_.GetWeakPtr(),
+                 base::Owned(new ScopedJavaGlobalRef<jobject>(
+                     env, obj)),
+                 base::Owned(new ScopedJavaGlobalRef<jobject>(
+                     env, jcallback))));
+}
+
 void WebContentsAndroid::OnFinishGetContentBitmap(
     ScopedJavaGlobalRef<jobject>* obj,
     ScopedJavaGlobalRef<jobject>* callback,
@@ -689,4 +708,35 @@ void WebContentsAndroid::OnFinishGetContentBitmap(
                                                   response);
 }
 
+void WebContentsAndroid::OnFinishDownloadImage(
+    base::android::ScopedJavaGlobalRef<jobject>* obj,
+    base::android::ScopedJavaGlobalRef<jobject>* callback,
+    int id,
+    int http_status_code,
+    const GURL& url,
+    const std::vector<SkBitmap>& bitmaps,
+    const std::vector<gfx::Size>& sizes) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  ScopedJavaLocalRef<jobject> jbitmaps =
+      Java_WebContentsImpl_createBitmapList(env);
+  ScopedJavaLocalRef<jobject> jsizes =
+      Java_WebContentsImpl_createSizeList(env);
+  ScopedJavaLocalRef<jstring> jurl =
+      base::android::ConvertUTF8ToJavaString(env, url.spec());
+
+  for (const SkBitmap& bitmap : bitmaps) {
+    // WARNING: convering to java bitmaps results in duplicate memory
+    // allocations, which increases the chance of OOMs if DownloadImage() is
+    // misused.
+    ScopedJavaLocalRef<jobject> jbitmap = gfx::ConvertToJavaBitmap(&bitmap);
+    Java_WebContentsImpl_addToBitmapList(env, jbitmaps.obj(), jbitmap.obj());
+  }
+  for (const gfx::Size& size : sizes) {
+    Java_WebContentsImpl_createSizeAndAddToList(
+        env, jsizes.obj(), size.width(), size.height());
+  }
+  Java_WebContentsImpl_onDownloadImageFinished(
+      env, obj->obj(), callback->obj(), id,
+      http_status_code, jurl.obj(), jbitmaps.obj(), jsizes.obj());
+}
 }  // namespace content

content/browser/web_contents/web_contents_android.h

@@ -190,6 +190,14 @@ class CONTENT_EXPORT WebContentsAndroid
     return synchronous_compositor_client_;
   }
 
+  int DownloadImage(JNIEnv* env,
+                    const base::android::JavaParamRef<jobject>& obj,
+                    const base::android::JavaParamRef<jstring>& url,
+                    jboolean is_fav_icon,
+                    jint max_bitmap_size,
+                    jboolean bypass_cache,
+                    const base::android::JavaParamRef<jobject>& jcallback);
+
  private:
   RenderWidgetHostViewAndroid* GetRenderWidgetHostViewAndroid();
 
@@ -199,6 +207,15 @@ class CONTENT_EXPORT WebContentsAndroid
       const SkBitmap& bitmap,
       ReadbackResponse response);
 
+  void OnFinishDownloadImage(
+      base::android::ScopedJavaGlobalRef<jobject>* obj,
+      base::android::ScopedJavaGlobalRef<jobject>* callback,
+      int id,
+      int http_status_code,
+      const GURL& url,
+      const std::vector<SkBitmap>& bitmaps,
+      const std::vector<gfx::Size>& sizes);
+
   WebContentsImpl* web_contents_;
   NavigationControllerAndroid navigation_controller_;
   base::android::ScopedJavaGlobalRef<jobject> obj_;

content/public/android/BUILD.gn

@@ -197,6 +197,7 @@ android_library("content_java") {
     "java/src/org/chromium/content_public/browser/AccessibilitySnapshotNode.java",
     "java/src/org/chromium/content_public/browser/ContentBitmapCallback.java",
     "java/src/org/chromium/content_public/browser/GestureStateListener.java",
+    "java/src/org/chromium/content_public/browser/ImageDownloadCallback.java",
     "java/src/org/chromium/content_public/browser/JavaScriptCallback.java",
     "java/src/org/chromium/content_public/browser/LoadUrlParams.java",
     "java/src/org/chromium/content_public/browser/NavigationController.java",

content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java

@@ -18,12 +18,15 @@ import org.chromium.base.annotations.JNINamespace;
 import org.chromium.content_public.browser.AccessibilitySnapshotCallback;
 import org.chromium.content_public.browser.AccessibilitySnapshotNode;
 import org.chromium.content_public.browser.ContentBitmapCallback;
+import org.chromium.content_public.browser.ImageDownloadCallback;
 import org.chromium.content_public.browser.JavaScriptCallback;
 import org.chromium.content_public.browser.NavigationController;
 import org.chromium.content_public.browser.WebContents;
 import org.chromium.content_public.browser.WebContentsObserver;
 import org.chromium.ui.accessibility.AXTextStyle;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.UUID;
 
 /**
@@ -469,6 +472,39 @@ import java.util.UUID;
         nativeReloadLoFiImages(mNativeWebContentsAndroid);
     }
 
+    @Override
+    public int downloadImage(String url, boolean isFavicon, int maxBitmapSize,
+            boolean bypassCache, ImageDownloadCallback callback) {
+        return nativeDownloadImage(mNativeWebContentsAndroid,
+                url, isFavicon, maxBitmapSize, bypassCache, callback);
+    }
+
+    @CalledByNative
+    private void onDownloadImageFinished(ImageDownloadCallback callback, int id, int httpStatusCode,
+            String imageUrl, List<Bitmap> bitmaps, List<Rect> sizes) {
+        callback.onFinishDownloadImage(id, httpStatusCode, imageUrl, bitmaps, sizes);
+    }
+
+    @CalledByNative
+    private static List<Bitmap> createBitmapList() {
+        return new ArrayList<Bitmap>();
+    }
+
+    @CalledByNative
+    private static void addToBitmapList(List<Bitmap> bitmaps, Bitmap bitmap) {
+        bitmaps.add(bitmap);
+    }
+
+    @CalledByNative
+    private static List<Rect> createSizeList() {
+        return new ArrayList<Rect>();
+    }
+
+    @CalledByNative
+    private static void createSizeAndAddToList(List<Rect> sizes, int width, int height) {
+        sizes.add(new Rect(0, 0, width, height));
+    }
+
     // This is static to avoid exposing a public destroy method on the native side of this class.
     private static native void nativeDestroyWebContents(long webContentsAndroidPtr);
 
@@ -530,4 +566,7 @@ import java.util.UUID;
             float x, float y, float width, float height);
     private native void nativeOnContextMenuClosed(long nativeWebContentsAndroid);
     private native void nativeReloadLoFiImages(long nativeWebContentsAndroid);
+    private native int nativeDownloadImage(long nativeWebContentsAndroid,
+            String url, boolean isFavicon, int maxBitmapSize,
+            boolean bypassCache, ImageDownloadCallback callback);
 }

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

+// 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);
+}

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

@@ -361,4 +361,24 @@ public interface WebContents extends Parcelable {
      * Reloads all the Lo-Fi images in this WebContents.
      */
     public void reloadLoFiImages();
+
+    /**
+     * Sends a request to download the given image {@link url}.
+     * This method delegates the call to the downloadImage() method of native WebContents.
+     * @param url The URL of the image to download.
+     * @param isFavicon Whether the image is a favicon. If true, the cookies are not sent and not
+     *                 accepted during download.
+     * @param maxBitmapSize The maximum bitmap size. Bitmaps with pixel sizes larger than {@link
+     *                 max_bitmap_size} are filtered out from the bitmap results. If there are no
+     *                 bitmap results <= {@link max_bitmap_size}, the smallest bitmap is resized to
+     *                 {@link max_bitmap_size} and is the only result. A {@link max_bitmap_size} of
+     *                 0 means unlimited.
+     * @param bypassCache If true, {@link url} is requested from the server even if it is present in
+     *                 the browser cache.
+     * @param callback The callback which will be called when the bitmaps are received from the
+     *                 renderer.
+     * @return The unique id of the download request
+     */
+    public int downloadImage(String url, boolean isFavicon, int maxBitmapSize,
+            boolean bypassCache, ImageDownloadCallback callback);
 }