fix link preview

app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewRepository.java

@@ -145,7 +145,7 @@ public class LinkPreviewRepository implements InjectableType {
           imageUrl = Optional.absent();
         }
 
-        if (imageUrl.isPresent() && !LinkPreviewUtil.isVaildMimeType(imageUrl.get())) {
+        if (imageUrl.isPresent() && !LinkPreviewUtil.isValidMimeType(imageUrl.get())) {
           Log.i(TAG, "Image URL was invalid mime type. Skipping.");
           imageUrl = Optional.absent();
         }

app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewUtil.java

@@ -98,11 +98,15 @@ public final class LinkPreviewUtil {
     }
   }
 
-  public static boolean isVaildMimeType(@NonNull String url) {
+  public static boolean isValidMimeType(@NonNull String url) {
-    String[] vaildMimeType = {"jpg", "png", "gif", "jpeg"};
+    String[] validMimeType = {".jpg", ".png", ".gif", ".jpeg"};
     if (url.contains(".")) {
-      String extenstion = url.substring(url.lastIndexOf(".") + 1).toLowerCase();
+      for (String mimeType : validMimeType) {
-      return Arrays.asList(vaildMimeType).contains(extenstion);
+        if (url.contains(mimeType)) {
+          return true;
+        }
+      }
+      return false;
     }
     return true;
   }