[Downloads] Handle externally deleted items

chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryItemWrapper.java

Index: chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryItemWrapper.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryItemWrapper.java b/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryItemWrapper.java
index 7b5c3682b62dd8c2407c702c1ba7eaa89d38e72c..9e810225fbfe8e0624d262c2b73b5965e8e87c6f 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryItemWrapper.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryItemWrapper.java
@@ -14,6 +14,7 @@ import android.net.Uri;
 import android.os.AsyncTask;
 import android.text.TextUtils;
 
+import org.chromium.base.Callback;
 import org.chromium.base.ContextUtils;
 import org.chromium.base.Log;
 import org.chromium.chrome.R;
@@ -62,8 +63,17 @@ abstract class DownloadHistoryItemWrapper implements TimedItem {
     /** Called when the user wants to open the file. */
     abstract void open();
 
-    /** Called when the user wants to delete the file. */
-    abstract void delete();
+    /**
+     * Called when the user wants to delete the file.
+     * @param callback The Callback to be notified when the item is finished being deleted.
+     */
+    abstract void delete(Callback<Void> callback);
+
+    /**
+     * @return Whether the file associated with this item has been removed through an external
+     *         action.
+     */
+    abstract boolean hasBeenExternallyRemoved();
 
     /** Wraps a {@link DownloadItem}. */
     static class DownloadItemWrapper extends DownloadHistoryItemWrapper {
@@ -169,7 +179,7 @@ abstract class DownloadHistoryItemWrapper implements TimedItem {
         }
 
         @Override
-        public void delete() {
+        public void delete(final Callback<Void> callback) {
             // Tell the DownloadManager to remove the file from history.
             DownloadManagerService service = DownloadManagerService.getDownloadManagerService(
                     ContextUtils.getApplicationContext());
@@ -185,6 +195,11 @@ abstract class DownloadHistoryItemWrapper implements TimedItem {
                     }
                     return null;
                 }
+
+                @Override
+                public void onPostExecute(Void unused) {
+                    callback.onResult(unused);
+                }
             }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
         }
 
@@ -207,6 +222,11 @@ abstract class DownloadHistoryItemWrapper implements TimedItem {
                 return DownloadFilter.FILTER_OTHER;
             }
         }
+
+        @Override
+        boolean hasBeenExternallyRemoved() {
+            return mItem.hasBeenExternallyRemoved();
+        }
     }
 
     /** Wraps a {@link OfflinePageDownloadItem}. */
@@ -281,8 +301,15 @@ abstract class DownloadHistoryItemWrapper implements TimedItem {
         }
 
         @Override
-        public void delete() {
+        public void delete(Callback<Void> callback) {
             mBridge.deleteItem(getId());
+            callback.onResult(null);
+        }
+
+        @Override
+        boolean hasBeenExternallyRemoved() {
+            // We don't currently detect when offline pages have been removed externally.
+            return false;
         }
     }
 }