Android: Fix warnings

TBR=sakal@webrtc.org

Bug: webrtc:6597,webrtc:8534
Change-Id: I39f96d9e0e6d604051b1cc13368dd44fc82b30b0
Reviewed-on: https://webrtc-review.googlesource.com/23622
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20719}
diff --git a/sdk/android/api/org/webrtc/MediaConstraints.java b/sdk/android/api/org/webrtc/MediaConstraints.java
index 1e74bcf..259d546 100644
--- a/sdk/android/api/org/webrtc/MediaConstraints.java
+++ b/sdk/android/api/org/webrtc/MediaConstraints.java
@@ -10,7 +10,7 @@
 
 package org.webrtc;
 
-import java.util.LinkedList;
+import java.util.ArrayList;
 import java.util.List;
 
 /**
@@ -63,8 +63,8 @@
   public final List<KeyValuePair> optional;
 
   public MediaConstraints() {
-    mandatory = new LinkedList<KeyValuePair>();
-    optional = new LinkedList<KeyValuePair>();
+    mandatory = new ArrayList<KeyValuePair>();
+    optional = new ArrayList<KeyValuePair>();
   }
 
   private static String stringifyKeyValuePairList(List<KeyValuePair> list) {