[OfflinePages] Make website settings popup rely on asynchronous API

chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java

Index: chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java b/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java
index e15e901b282ecccb34cdc1daedcf31757850d780..b623a95283481b56b58150c89ffe3ec0165ea444 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java
@@ -98,6 +98,16 @@ public class OfflinePageBridge {
     }
 
     /**
+     * Callback that delivers information about one offline page entry.
+     *
+     * The returned item will be null if no items are found.
+     */
+    public interface SingleOfflinePageItemCallback {
+        @CalledByNative("SingleOfflinePageItemCallback")
+        void onResult(OfflinePageItem item);
+    }
+
+    /**
      * Callback used when determining whether we have any offline pages.
      */
     public interface HasPagesCallback {
@@ -346,34 +356,31 @@ public class OfflinePageBridge {
     @VisibleForTesting
     public void getPagesByOfflineUrl(
             final String offlineUrl, final MultipleOfflinePageItemCallback callback) {

[dewittj, 2016/05/16 21:07:46]

Let's just remove this method, since we have the constraint that only one
offline page can point to a local file:// URL.

[chili, 2016/05/16 23:06:41]

Done.

-        runWhenLoaded(new Runnable() {
-            @Override
-            public void run() {
-                List<OfflinePageItem> result = new ArrayList<>();
-
-                // TODO(http://crbug.com/589526) This native API returns only one item, but in the
-                // future will return a list.
-                OfflinePageItem item =
-                        nativeGetPageByOfflineUrl(mNativeOfflinePageBridge, offlineUrl);
-                if (item != null) {
-                    result.add(item);
-                }
-
-                callback.onResult(result);
-            }
-        });
+        nativeGetPageByOfflineUrl(
+                mNativeOfflinePageBridge,
+                offlineUrl,
+                new SingleOfflinePageItemCallback() {
+                    @Override
+                    public void onResult(OfflinePageItem item) {
+                        List<OfflinePageItem> result = new ArrayList<>();
+                        if (item != null) {
+                            result.add(item);
+                        }
+                        callback.onResult(result);
+                    }
+                });
     }
 
     /**
-     * Gets an offline page associated with a provided offline URL.
-     * This method is deprecated. Use OfflinePageBridge#getPagesByOnlineUrl.
+     * Get the offline page associated with the provided offline URL.
      *
      * @param string URL pointing to the offline copy of the web page.
-     * @return An {@link OfflinePageItem} matching the offline URL or
-     * <code>null</code> if not found.
+     * @param SingleOfflinePageItemCallback callback to pass back the
+     * matching {@link OfflinePageItem}, if any.

[dewittj, 2016/05/16 21:07:46]

nit: please mention that null is possible in the callback.

[chili, 2016/05/16 23:06:41]

Assuming you mean to add @Nullable reference in callback?

[dewittj, 2016/05/17 17:36:02]

I was thinking in this comment.  But you did that too :)

      */
-    public OfflinePageItem getPageByOfflineUrl(String offlineUrl) {
-        return nativeGetPageByOfflineUrl(mNativeOfflinePageBridge, offlineUrl);
+    public void getPageByOfflineUrl(
+            String offlineUrl, SingleOfflinePageItemCallback callback) {
+        nativeGetPageByOfflineUrl(mNativeOfflinePageBridge, offlineUrl, callback);
     }
 
     /**
@@ -628,8 +635,10 @@ public class OfflinePageBridge {
     native OfflinePageItem nativeGetPageByOfflineId(long nativeOfflinePageBridge, long offlineId);
     private native OfflinePageItem nativeGetBestPageForOnlineURL(
             long nativeOfflinePageBridge, String onlineURL);
-    private native OfflinePageItem nativeGetPageByOfflineUrl(
-            long nativeOfflinePageBridge, String offlineUrl);
+    private native void nativeGetPageByOfflineUrl(
+            long nativeOfflinePageBridge,
+            String offlineUrl,
+            SingleOfflinePageItemCallback callback);
     private native void nativeSavePage(long nativeOfflinePageBridge, SavePageCallback callback,
             WebContents webContents, String clientNamespace, String clientId);
     private native void nativeSavePageLater(