Fix mistake in obtaining DownloadsFilter icons by file type.

Previously, |getIconResId| returned 36dp |text| icon, when it was
supposed to return |file| icon. This CL fixes this.

Bug:726611

Change-Id: I8763d313185ae6bdc2854a776f831b4900e7310b
Reviewed-on: https://chromium-review.googlesource.com/517062Reviewed-by: Min Qin <qinmin@chromium.org>
Reviewed-by: Theresa Wellington <twellington@chromium.org>
Commit-Queue: vitaliii <vitaliii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#476223}

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

@@ -834,7 +834,7 @@ public class DownloadUtils {
                                                    : R.drawable.ic_drive_text_white_36dp;
             default:
                 return iconSize == ICON_SIZE_24_DP ? R.drawable.ic_drive_file_white_24dp
-                                                   : R.drawable.ic_drive_text_white_36dp;
+                                                   : R.drawable.ic_drive_file_white_36dp;
         }
     }