Work around an issue that Content uri from DownloadManager is not working for other apps

On certain android versions, content URI from the DownloadManager can not be read by other apps
This CL works around the problem by using the file uri.

BUG=722383

Change-Id: I30ee7ab0ad16f9e13a5d43a1b1f50fe7425078ad
Reviewed-on: https://chromium-review.googlesource.com/530047
Commit-Queue: Min Qin <qinmin@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Cr-Commit-Position: refs/heads/master@{#478694}

chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerService.java

@@ -18,6 +18,7 @@ import android.support.annotation.Nullable;
 import android.text.TextUtils;
 import android.util.Pair;
 
+import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.base.ContextUtils;
 import org.chromium.base.Log;
 import org.chromium.base.ObserverList;
@@ -737,8 +738,9 @@ public class DownloadManagerService
             Context context, @Nullable String filePath, long downloadId,
             boolean isSupportedMimeType) {
         assert !ThreadUtils.runningOnUiThread();
-        Uri contentUri = DownloadManagerDelegate.getContentUriFromDownloadManager(
-                context, downloadId);
+        Uri contentUri = filePath == null
+                ? DownloadManagerDelegate.getContentUriFromDownloadManager(context, downloadId)
+                : ApiCompatibilityUtils.getUriForDownloadedFile(new File(filePath));
         if (contentUri == null) return null;
 
         DownloadManager manager =