Fix safe key caching.

library/src/main/java/com/bumptech/glide/load/engine/cache/SafeKeyGenerator.java

@@ -9,10 +9,13 @@ import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 
 public class SafeKeyGenerator {
-    private final LruCache<Key, String> loadIdToSafeHash = new LruCache<Key, String>(250);
+    private final LruCache<Key, String> loadIdToSafeHash = new LruCache<Key, String>(1000);
 
     public String getSafeKey(Key key) {
-        String safeKey = loadIdToSafeHash.get(key);
+        String safeKey;
+        synchronized (loadIdToSafeHash) {
+            safeKey = loadIdToSafeHash.get(key);
+        }
         if (safeKey == null) {
             try {
                 MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
@@ -23,6 +26,9 @@ public class SafeKeyGenerator {
             } catch (NoSuchAlgorithmException e) {
                 e.printStackTrace();
             }
+            synchronized (loadIdToSafeHash) {
+                loadIdToSafeHash.put(key, safeKey);
+            }
         }
         return safeKey;
     }