Fix b/5353417 Images downloaded from browser are showing incorrect details (Time is shown as dec 31 1969)

MediaScanner sets DATE_TAKEN with EXIF's datetime tag value. When this information is not available,
ExifInterface will simply return -1 which is accidentally used by MediaScanner.

Adding a check to avoid it so MediaProvider can calculate the date taken from last modified time instead.

Change-Id: I305b93a6c5602cbb9f97c3bbd384d358bda030c6

Author: Ray Chen

media/java/android/media/MediaScanner.java

@@ -839,7 +839,7 @@ private Uri endFile(FileEntry entry, boolean ringtones, boolean notifications,
                         // and EXIF local time is not less than 1 Day, otherwise MediaProvider
                         // will use file time as taken time.
                         time = exif.getDateTime();
-                        if (Math.abs(mLastModified * 1000 - time) >= 86400000) {
+                        if (time != -1 && Math.abs(mLastModified * 1000 - time) >= 86400000) {
                             values.put(Images.Media.DATE_TAKEN, time);
                         }
                     }
@@ -1183,7 +1183,7 @@ private void pruneDeadThumbnailFiles() {
 
     static class MediaBulkDeleter {
         StringBuilder whereClause = new StringBuilder();
-        ArrayList<String> whereArgs = new ArrayList<String>(100); 
+        ArrayList<String> whereArgs = new ArrayList<String>(100);
         IContentProvider mProvider;
         Uri mBaseUri;